@documentally at yesterday's DM:EX event in Manchester. He touched on loads of interesting aspects of Social Media stuff including some comments about his own striking avatar, it's pros and cons and the benefits of sticking with it.
Faces, portions of faces and something distinct in terms of colour, style etc seems key, but using it across all social media channels is also vital.
Not long ago I moved from a borrowed abstract photograph to a picture of myself. It's the one I use across most social media channels, except this blog and Facebook, where the pics are so much bigger and my avatar look so much scarier. I quite like the idea of using this pic as an avatar.
But won't be doing.