Traveling with friends can be a total pain, from agreeing on whether to stay in a hotel or a hostel, to arguing over just how hot the chicks at the disco will have to be to make the sex worth totally having your head cut off. Instead hooking you up with agreeable strangers, GlobeTrooper.
A social network matching up travelers with kindred jet-setters the world over, GT was recently launched by a pair Aussies who couldn't find a friend who'd climb Mt. Kilimanjaro with them, and sagely reasoned the best spot to source someone at the pinnacle of human endurance was the same place that provides an unending stream of people banging. Potential trips/travel partners can be narrowed by destination regions, activities (from Sailing & Cruising to Food/Wine), and time frame, or ensnare others in your own vacation venus flytrap by picking a location(s), setting likely dates/budget/activities, and rating the whole shebang on four criteria -- difficulty, remoteness, risk, and "Culture Shock", though if it's anything like Future Shock, your only friend will still be your own Hancock. Current posted adventures include everything from a ride on the Trans-Siberian Railroad from Moscow to Beijing; a New Year's sojourn to Rio; a 4-month excursion in a Land Rover from London to Cape Town; a journey through the Alps that includes hang gliding in Switzerland; and a trek through China's Huashan Trail, considered by many to be the deadliest hike in the world (so hopefully your GORP stands for Good Old Raisins and Penicillin).
For those fishing for ideas, each destination region offers a section stocked with suggestions for "Must See" and "Must Do", which in Eastern Europe definitely includes chicks in clubs, cause they can totally pull off the best head.