Banknotes featuring scientists and mathematicians. Including the two in-print US bills that we're all least likely to see: the $100 (Franklin) and the $2 (Jefferson). For the non-US readers: the $100 is the largest bill in general circulation. For some reason the $2 bill has fallen out of favor, and although it's legal it's very rare, to the point that some people don't know about them and urban legends circulate about the $2 being suspected as counterfeit)
There seem to be more "scientists" than "mathematicians" on the list, but this may just reflect the fact that there are more scientists than mathematicians in general. In fact, "scientist" is a broad enough category that I don't think too many people would describe themselves as "scientists" when asked "what do you do?", rather responding with something like "physicist" or "biologist"; but I think a lot of mathematicians would answer "I'm a mathematician" to this question. (This seems to correspond roughly with the way departments are organized in most universities; there's usually a "department of mathematics" but very rarely a "department of science".)
(via a comment at Gil Kalai's blog)
Edit, 6:20 pm: the linguists seem to be compiling their own list of linguists-on-money, over at Language Log.