Stealth (SSH-based Trust Enhancement Acquired through a Locally Trusted Host) is a file integrity scanner. It differs from a program like Tripwire in that it does not require the use of read-only media or modifiable logs. It leaves (almost) no trace on the computer being checked. It is very difficult for intruders to detect or evade, and cannot be modified by intruders. It can be used to perform integrity checks on many computers without a heavy maintenance burden. It can be used without being installed on the target computer.
capictcha generates CAPTCHA images from arbitrary strings. It supports the use of any TrueType/OpenType font and an alternate (more stable) font for punctuation and other characters, and allows you to specify the size and output text, JPG or PNG graphic output, and MD5 lookups of values you don't want to expose as plain text (which could be used to give a simple text table relating email addresses to their hex MD5 hash). Individual character tweaks, overstriking, and random lines are easily configurable.