While some of my colleagues at Offline accused me of multiple personality disorder for having so many avatars, I do like to play around with them and change them to meet my mood.
My favorite avatar at the moment is the South Park character I created:
This is a librarian with an attitude. I like her because she sums up my perspective after working with E-Rate for so long. Send her to DC and she'll clean up the program.
You can create your own South Park character at South Park Studios
Try it, it's fun!
I've also created a Simpsons character.
You can blame Stephen Abrams for these creative wastes of time.
One thing about these is they're created in Flash so the avatar is not readily downloaded. I got around this by taking a screenshot - clicking the Print Screen or PrtSc key. This takes an image of the entire screen. You can then paste the entire screen image into a graphics program like MS Paint and crop it to get just the avatar. I'd save it as a JPEG file.
Finally, there are Yahoo avatars. You need to have a Yahoo account to create these. But there are lots of different outfits, hairstyles, backgrounds, pets, etc. This is one I created for winter - taking my penguin for a walk. You can use these all over the Yahoo site as well as export them to your web page or blog and/or download for use on other sites that use images.
The only one that I won't share is my Second Life avatar because I hate that one. As vain as it might be, it's the reason I won't bother with Second Life. I think my South Park avatar needs to go in there and get things in order before I'll spend any time there.