Here's an invitation to post a better image of your PsychCentral alter-ego than what fits in the little box beside your posts.
Or maybe you want to show something a little different. Anything that symbolizes you or your online presence in some way.
Cepheid Variables are interesting stars used for astrometrics. However, my default avatar is actually a compass rose ... partly because of symbolism involving mapping and finding your way. But mainly because I couldn't find a star image I liked quickly enough at the time. Now I like it and would rather not change it.
So here's an over-the-top depiction of a variable star. (Ooh, mood swings

)