Can you?

Is there any way to check your character or look up other peoples characters without being in game? I am trying to figure out the name of my guild, and I cannot remember anything about it except for the name of one of the people in it.

No....

Xfire (http://www.xfire.com/) supports Guild Wars. I've never used it, but in theory, you can see your game friends on line and what they're playing. Then by doing something like clicking their name you can join the game they're in. Like I said, I don't use it, but that's the claim on the web site.