Intro
RT, the helpdesk system uses mysql, apache, and sendmail all together.
RTFM: Request Tracker FAQ Manager, is an addon to RT that allows to easily and quickly write documentations.

Mailing List/Request Tracker Web Page
http://lists.bestpractical.com/cgi-bin/htsearch
http://www.bestpractical.com/

Requirements
Perl
Mysql
Apache with mod_perl
sendmail

Installation Instructions
Make sure your proxy environment variables set, ie: http_proxy, ftp_proxy
Download the source code from:
http://download.bestpractical.com/pub/rt/release/rt.tar.gz
Extract the file.
./configure --prefix=/usr/local/rt3
make testdeps
make fixdeps (keep doing this step until it perl downloads all the perl modules)
make install
make initialize-database
perl -MCPAN -e'install Apache::DBI'

Put rt3.conf in /etc/httpd/conf.d/
Add aliases from aliases into /etc/mail/aliases, run newaliases afterwards

Request Tracker issues
After updating apache, perl modules may get out of sync and you'll see this error in /var/log/httpd/*error_log:

Can't locate object method "content_type" via package "Apache2::RequestRec" at /usr/local/rt3/bin/webmux.pl line 109.\n

Run this to fix it: perl -MCPAN -e 'install Bundle::Apache2'