The contrib directory contains the following programs:

Guardian - a script that automatically reconfigures ipchains firewalls based on Snort alerts

address_config.sh - made by a laptop user that changes his IP configuration frequently, allows Snort to change its address space quickly and painlessly as well

snortlog - perl script that provides syslog alert summaries and reverse attacker name resolution

snort_stat.pl - perl script that provides a statistical analysis of syslog alerts produced by Snort

snort2html - generates web pages from snort alerts

snortsnarf.pl -  Code to parse a file of snort alerts and produce HTML output intended for diagnostic inspection and tracking down problems.  The model is that one is using a cron job or similar to produce a daily/hourly/whatever file of snort alerts.  This script can be run on each such file to produce a convenient HTML breakout of all the alerts.

snort-sort.pl - this script produces a sorted list of snort alerts from a snort alert file

snortwatch-0.7 - This is a little tool to help keep track of alerts generated by the excellent IDS tool snort. I've mostly tested snortwatch against version 1.5.x of snort and although the output of 1.6 seems very similar if not to say identical, there may still be some type of alert I haven't come across that could throw off the parsing. 
