Before there was Triptrotting and Airbnb, there was a nonprofit called CouchSurfing. Founded in 1999 as a project to help travelers find people and places to stay along their journeys, then in 2003, CouchSurfing saw the opportunity to become a corporation that could dedicate more time and effort to the endeavors of couch surfing travel -- oh, if only you could travel by couch. 

Now, CouchSurfing has announced a $15 million Series B Round from General Catalyst Partners, Menlo Ventures,Benchmark Capital and Omidyar Network.

The new funding brings the social travel network’s total funds raised to $22.6 million. 

With nearly 5 million users in more than 93,000 cities, and at least 40,000 interest groups that host activities, CouchSurfing is a force to be reckoned with. New CEO Tony Espinoza joined the company 5 months ago and has been on a mission to rejigger the infrastructure to the service and support the exceptional growth it is experiencing.

In the last year, the company has added two million more members and has seen a new group of people using its site as a (sometimes) cheaper alternative to Airbnb.

While the basic service is free, users can pay a one-time fee of $25 to verify their identity and location. 

With a still very nimble team of just 30 employees, the company has recently entered the mobile world with its applications.

Back in March, a traveling community platform, Triptrotting, announced that it landed a $1 million Series A round of funding. The latest round was included funds from Google Ventures, Mark Suster (LaunchpadLA), Dave McClure (500 Startups), Bill Gross (Idealab), WI Harper Group, Safa Rashtchy, Eric Chen and other angel investors bringing its total funding to $1.3 million to date.

Triptrotting has a similar focus on connecting people that CouchSurfing does, and it tries to empower travelers before they board a flight to a far-away land by connecting them with people that live in their desired destination.  

The level of connection and information can range from actually hosting a traveler at your house to taking them on a tour or just communicating online and then meeting for a coffee when they arrive.

One of the most interesting aspects of this travel network is just how closely it is tied to matching sites like eHarmony, since Triptrotting utilizes algorithms to match travelers with hosts. But this could also be because the Triptrotting math was developed in consultation with former eHarmony chief scientist Galen Buckwalter.

While the service is mostly about helping travelers have a more informed and cultural experience, hosts can ask to be paid tips for specific services such as serving as a tour guide.

And another site, Tripl.com, secured $300,000 last summer, which was just getting started as an evolution of another site: Vacation Relation. Tripl is about creating a more social and global world through the experience of travel. Tripl connects recommended travelers, locals, and people connected to your existing social networks. Their platform is available for both consumers and online travel businesses.