I like +Flattr - social micropayments but it kind of annoys me that my crappy avatar is served from Gravatar.com, so all of those juicy statistics about what people access on flattr and how that correlates with other places referring to Gravatar... well, OK, maybe I'm paranoid.
On the other hand there is an alternative which I think more people need to be aware of, and especially which more free software projects should use in preference to Gravatar.com.
In my opinion Libravatar is a very well-thought-out project. Not only does it address the privacy issues of Gravatar, but it also provides some noticeable technological improvements on the way.