I regularly use about a dozen different social web services, with dozens more that I have accounts on. Historically, I've used one of a very small number of photos of myself as my avatar or user icon on these websites.
The other evening, I spent about an hour replacing my image on as many sites as I could find, because I thought it was time to replace my photo with a picture I discovered a few weeks ago. It's the awesomest photo ever.

'Sup, dog?
welcome to last month
Duh, I knew about the picture before last month. But I couldn't use it as my avatar then because I had to wait until it was the right time! Sheesh.
Nice! I hate finding photos which look good enough as avatars.
uhm, the other end of that chain goes, where...?
Haha. Too awesome :-)
That is one cute dog!
Hey, I love dogs anyway.