Location: Mountain View, California

What is is: A cloud service that lets different videoconferencing systems work with each other. So whether you're on your cell phone or computer, using Skype, Google Hangouts, or Polycom, you can talk to everyone else in a meeting.

Date founded: 2009

Company size: 200 employees

Financing: $99 million from Accel Partners, Norwest Venture Partners, New Enterprise Associates, and Battery Ventures.

Why it's a good bet: Cloud startups are hot and Blue Jeans Network might be the hottest of them all. The company has grown to between a third and a half of the video conferencing market in less than three years, and continues to grow quickly. With customers include mom-and-pop businesses, colleges like Stanford and UC Berkeley, and big leaguers like Facebook. Plus, earlier this year, the company put up some snarky billboards chiding Yahoo for banning telecommuting. Sounds like a fun place to work.

Location: New York

What is is: Rebel Mouse is a platform that allows users to pull their content together from across social networks.

Date founded: 2012

Company size: Around 35 employees

Financing: $12.8 million from the likes of First Round Capital, Lerer Ventures, Oak Investment Partners, and Buzzfeed's Jonah Peretti.

Why it's a good bet: Big brands and publications (like GE and ESPN magazine) have started using Rebel Mouse. The site had 7 million unique visitors per month as of August, a 900% leap since the beginning of the year. Plus, Rebel Mouse recently announced a series of hires, and since the team is expanding, it could be a good time to try to hop on.

Location: San Francisco, CA

What it is: Photo sharing, saving and discovery site.

Date founded: 2008

Company size: 180

Financing: $338 million from Jack Abraham, Michael Birch, Scott Belsky, Shana Fisher, Kevin Hartz, Jeremy Stoppelman, Brian Cohen, Fritz Lanman, Hank Vigil, FirstMark Capital, Bessemer Venture Partners, Max Levchin, Ron Conway, Andreessen Horowitz, Rakuten

Why it's a good bet: With billions of monthly pageviews and so few employees, Pinterest is a company that is driving discovery commerce. It's one of the top referral sites on the web and its users are rabid. As far as startups go, Pinterest is the closest you can come to a sure bet.

Location: San Francisco

What it is: A mobile payments company

Date founded: 2009

Company size: 200 employees

Financing: $341 million from Khosla Ventures, Greg Yaitanes, Marissa Mayer, Dennis Crowley, Kevin Rose, First Round Capital, Ron Conway, Biz Stone, Joshua Schachter, Shawn Fanning, Zachary Bogue, Andrew Rasiej, David Lee, Esther Dyson, robin Chan, Fritz Lanman, Brian Pokorny, Xavier Niel, Jim Pitkow, Sequoia Capital, Visa, KPCB, Tiger Globla, Richard Branson, Starbucks, CrunchFund, Citi Ventures, Rizvi Traverse Management

Why it's a good bet: You might not get a ton of equity if you join Square now, since it has raised hundreds of millions of dollars and has hundreds of employees. But Square is undoubtedly one of the most promising startups right now. Jack Dorsey, its CEO, co-founded Twitter and it's onboarding small businesses quickly.

The company also just released a new way to send cash via email, proving that you the company will keep innovating in the mobile payments space.

Location: Mountain View, CA

What is it: A NoSQL database technology.

Date founded: 2009

Company size: More than 100 employees

Financing: $56 million from Accel Partners, Ignition Partners, Adams Street Partners, and others.

Why it's a good bet: Couchbase has over 350 high-paying customers and hsa seen a lot of growth—a 400% sales increase at the end of August. It also recently announced a new mobile strategy that makes it the first vendor with a NoSQL database for mobile devices.

Location: San Francisco, CA

What it is: Real-time picture chatting.

Date founded: 2011

Company size: Under 20.

Financing: $73 million from Lightspeed Venture Partners, Benchmark, General Catalyst Partners, Institutional Venture Partners, and SV Angel.

Why it's a good bet: Look on any college kid's smart phone and you're likely to see Snapchat installed. The company just released a new feature (Snapchat stories) that opens up new doors for brands (which could mean advertising revenue down the line). There's a big opportunity to join now and become a part of a potentially huge mobile company.

Location: New York (with central team members in Boston)

What is it: A company that allows you to access live broadcast television on Internet-connected devices.

Date founded: 2011

Company size: Around 50 employees

Financing: $68 million from FirstMark Capital, First Round Capital, High Line Venture Partners, and SV Angel.

Why it's a good bet: Aereo is growing incredibly fast and expanding into 22 new markets this year. Plus, according to Glassdoor, the company is currently hiring.

Location: Brooklyn, NY

What is is: A website that explains the meanings of—primarily rap—lyrics, with ambitions to annotate everything from legal texts to political speeches.

Date founded: 2009

Company size: Less than 10 employees

Financing: $16.8 million from betaworks, Andreessen Horowitz, and Alexis Ohanian

Why it's a good bet: When Marc Andreesen explained why he was investing in Rap Genius, he said it was one of the fastest growing websites in Y Combinator's history and run by a stellar team. The company has set its sights far beyond rap songs, so we look forward to seeing it grow. Plus, it could be extremely fun to work with Rap Genius' three young and errr... bold founders.

Location: Los Altos, CA

What is is: An online file sharing and cloud content management service

Date founded: 2009

Company size: Over 500

Financing: More than $200 million from Mark Cuban, Draper Fisher Jurvetson, US Venture Partners, Meritech Capital Partners, Andreessen Horowitz, Emergence Capital Partners, SAP, and General Atlantic.

Why it's a good bet: With a valuation of between $1 and $2 billion, Box sits pretty when it comes enterprise startups. The company is widely expected to IPO in 2014, so if you jump on the boat now and score some options, you could still make a pretty penny.

Location: New York

What it is: A company that makes renting apartments in NYC really easy.

Date founded: 2012

Company size: Around 35 employees

Financing: $33 million from Goldman Sachs, Thrive Capital, Founders Fund, 406 Ventures, and Advance Publications

Why it's a good bet: At about 5 months old, Urban Compass is already worth $150 million—with huge potential for growth outside of New York. Can't beat the leadership: it was founded by Ori Allon, whose past companies have been acquired by Google and Twitter.

Location: Los Angeles

What it is: An online-only vintage clothing company

Date founded: 2006

Company size: About 100

Financing: $49 million from Index Ventures.

Why it's a good bet: Nasty Gal has the potential to become the first digital-only, Forever 21 type brand. It's led by Sophia Amaruso, who bootstrapped the company after launching it on Ebay, and Deborah Benton, who has been called the Sheryl Sandberg of LA.

Location: New York

What it is: A social media company with good intentions.

Date founded: 2012

Company size: 22 employees

Financing: $12 million from Chris Hughes, Spark Capital, Catamount Ventures, Alexis Ohanian, New Enterprise Associates, Klee Irwin, and The Knight Foundation.

Why it's a good bet: The more often we see Upworthy's content going viral, the more we have faith that this company is going to just keep growing. The site boasted 19.8 million unique visitors between January and March.

Location: New York

What it is: Tinder helps you meet people by connecting you with only those near you.

Date founded: 2012

Company size: 25

Financing: Tinder was born in a startup lab controlled by InterActiveCorp, so investors haven't been able to touch it.

Why it's a good bet: Highly addictive, Tinder is currently the hot dating app that everyone's trying, and the buzz doesn't seem like it will die down anytime soon. Getting in now could be seriously worth it later.

Location: San Francisco and New York

What it is: A publishing platform that organizes text and images into theme-based collections

Date founded: 2012

Company size: Under 50

Financing: Biz Stone and Ev Williams of Twitter co-founded Medium, though they haven't revealed how much they've invested.

Why it's a good bet: Medium combines the best features from Pinterest, Tumblr, and Digg to let people express themselves without a word-count limit. This attempt to "re-imagine publishing" might just work.

Location: Des Moines, IA

What is it: A web platform that lets users send, receive, and request money for $0.25 per transaction.

Date founded: 2008

Company size: 15

Financing: $22.8 million from Andreessen Horowitz, Thrive Capital, Village Ventures, Union Square Ventures, BetterWorks, and more.

Why it's a good bet: Inevitably, there is an enormous future for easy Internet payments. We think that Dwolla has one of the best shots to tackle it.

Location: San Francisco, CA

What is it: A wearable sensor that tracks data about your calories burned, sleep quality, steps, and distance.

Date founded: 2007

Company size: Unknown

Financing: $66 million, including from True Ventures, Foundry Group, SoftTech VC, and Felicis Ventures

Why it's a good bet: In March, the company had a $300 million plus valuation, despite competing with Jawbone and Nike. When it comes to wearable health tech,FitBit is creating the greatest buzz on the scene right now.

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