This may sound lame, but are there any sites for people that want/need travel buddies?

None of my friends can/want to go anywhere ever, and some just can't afford it. Under normal cirstances I wouldn't be able to either, but I get free airfare wherever I want (I only have to pay tax) and I've never traveled out of the country.. or anywhere, really. I need to do get out and do more before life/time pes me by, but I don't have anyone to do it with. Mainly looking for someone to go to Europe with. I feel like I could take on London okay alone, but I'd rather not.. any other country such as Italy or France, I def. don't want to go it alone.. I'm not anywhere close to being knowledgeable or fluent and I don't want to get stuck in horrid situations with everything I have to encounter (at least not alone). Are there any sites or ways to find good, decent people to travel with? I guess kind of like a dating site, but for friends. Again, pathetic, I know, but I have no one willing to do anything big like this with me, so I have to find a way somehow before I decide to do it on my own. Also, if you've been to London, where would be a good place to stay for about a week? I mainly want to sight-see (Buckingham Palace, Westminster Abbey, etc), visit bars (pubs), etc.. not necessarily any tours.. I want to be able to venture out on my own for the week. Never done anything like this, so I don't know what to expect, how to get around, or anything. Any tips would be greatly appreciated! :)