Yes, I often find my pictures used by other people who have nicked them off my website and think it's OK to use them with asking me or giving me a picture credit or a link. Bastard thieves!
The worst ones are the ones that point their code at your website, so you end up hosting the damned picture for them too. This website is currently doing that: http://www.myspace.com/tencc
See the first photo? That's mine. And if you look at the properties, I'm frigging hosting it for them! I have emailed them to give 'em a chance to 1.apologise and grovel, and 2. remove it themselves, but so far, no cigar. So tonight I'll rename the pic and break the link.