Unmask is a python script that allows you to break the anonymity of e-mail or other text. It works by doing basic statistical matching against stored "signatures." It may require some tweaking to fit your particular use to it (un-anonymizing IRC chats, email, web pages on FreeNet, etc). Another fun parlor game use is using it to distinguish between two groups of any kind. Male/Female, Engineers/Computer Scientists, Scientists/Liberal Arts Majors, etc. If you improve it in some way, please send me (dave@immunitysec.com) a note. Unmask is released under the GNU GPL v2.0.