I use AdBlock Plus and while on the main forum page went to "Open blockable obljects". I saw many urls like this blog.outer-court.com/forum/image/ [insert username here] .gif which when I typed into my addressbar brought me to the page my little graphic Philipp assigned. In the [insert username here} you put your username. If there are spaces enter them as -. For example mine is http://blogoscoped.com/forum/image/james-xuan.gif

That only works for users with image :/
I only have "Forum author" image.
http://blogoscoped.com/forum/image/forum-author.gif

and why are you posting this?

Or you could just Right Click on the Image and choose "View Background Image".

I'm with stefan, why are you posting this?