Albert Huberts began noticing that there seemed to be a lot in common between people's twitter avatars. In December of 2012, he began collecting and categorizing Twitter avatars, and posting the results at avadenticals.org.
As he describes it, what he found was:
"we are not very original in how we present ourselves, to put it mildly. I have seen literally millions of avatars during the last year and the ones that stand out are few and far between. Most of us play it safe and imitate – consciously or subconsciously – other avatars."