This is for the PC version, I can't seem to start a game.  First, it seems not many others are hosting so that first tells me there may be a server issue, and since it's gamespy, iam not shocked if that's the issue.  First I either get timed out or go in, get disconnected after loading for ages then booted back to the lobby.  Anyone else having this issue? Any patch I don't know about?

I just went through a program named GameRanger, it has worked like a charm ever since. There also seems to be quite a few servers on there.

That sucks man, I've been playing the PS3 version but I get huge frame rate drops and the mics sometimes get big echos or major lag, I hope all of this is fixed up soon.

Yup press the Guide button then look down your friends list and invite. 
   
Oh wait the PC version, sorry missed that. 
 
What Fragstoff said. 
 
 
 
 
:P

Also, if you have Windows 7 you have an additional step.
Then use this.

This is what happens when your MP is hosted by gamespy.... It's hard to be a PC gamer these days. 

You would think if you wanted a game for people to have a great online experience online, and your game is sold on steam, you would use steam's online service, or as Jeff said, make your own online servers.  I am sure there is a larger issue somewhere onto why Gearbox did not use Steam, I just wish they could have shook hands with them and made an online MP experience that actually worked.  Other than that, the game is great.