I really LOVE your work, Tim!
While no artist, I play around with images and typography quite a lot. In another forum someone asked (but couldn't get an answer that would be 100% turstworthy), whether the A+ sign, modified from the Dawkins original A, was under copyright or free to be used on one's own blog, as an avatar etc.
Just in case, I came up with this:http://imgur.com/a/fue9s
I'll do some more (different colors, themes etc.) as I find time, and hereby declare that they are hereby free for all to use noncommercially =)