Here are links to some good U2-related sites.Screencaps and pictures
U2 Take Me Higher - Features a great, massive gallery of pictures.
Stuck in a Moment - Has lots of screencaps, especially of recent performances and videos.
PLEBA - An Interference forum where people post lots and lots of pictures of the band. An excellent source of pictures, especially current ones, but if you're not used to Bono fangirls, prepare for an...interesting experience!
Bono Online - Obviously it only has caps and pictures of Bono, but if that's what you want, it's a great source.
General U2 sites
@U2 - A great general U2 site.
U2log - Another great U2 news site.
Interference - Featuring news, lyrics, and huge (and hugely addicting) forums.
U2 Wanderer - The best site for U2's lyrics and discography.
U2 Vertigo Tour - Setlists from all of U2's tours.