Many of you have probably heard of a file integrity product called Tripwire - it's basically a file system monitoring tool that can detect any and all deviations from an established baseline, and can notify you of these changes. It's developed by a private company that spun off a GPL'd version for Linux a couple years ago, but continued to develop and offer a commercial version. Their recent versions have (not surprisingly) many significant improvements over the Open Source release, but this release still works quite well on individual systems.
I use this product regularly at work, and one of my few gripes has been the distinct lack of any Macintosh support. But recently, a kind developer from the Open Source community released an OS X patch!
I have assembled a functioning version complete with an installation script - you can read the instructions and download the bundle here. If you prefer to roll your own, the source code for this package is also available. This package is derived from the original source available on SourceForge under the Tripwire project, and the patch is available separately as well.
Mac OS X Hints
http://hints.macworld.com/article.php?story=20030928175059447