I noticed that ABP doesn't seem to be able to filter favicons. I didn't think it was necessary anyway until I stumbled upon this site
, which retrieves its favicon from gravatar.com.
I usually have a filter for gravatar avatars on third-party sites, and I was surprised to see this is my firewall logs: http://0.gravatar.com/blavatar/6bc93f43 ... 631f7?s=16
Now considering it's a get request able to send custom parameters along with headers, useragent, referrer and IP, shouldn't ABP be able to block favicons just like any web bug? Favicons loaded from external sites seem to be pretty rare and not abused to track people, but still, the possibility is there.