frank-
are these photographs that you have taken or random ones off the web?
Almost all of the avatar photos so far have been from
PHOTOCASE. It's a former German photography site that is now crossing over into English. I go there a lot for visual inspiration as the photos are always very diverse and often experimental. If you sign up you get a certain amount of free photos to download over a certain time period and then if you upload some yourself you get so many downloads for each uploaded photo. I love the creativity. It has a definite European vibe to the photos that you don't get elsewhere.
What's interesting is that the photos are getting inherently better as digital cameras improve. If you go through their old back catalogue you can see the progression of improvement as people get new and better technology for taking photos.