Some software you might want consider:
* Little Snitch - software to monitor/control incoming/outgoing internet connections (not free)
* ClamXav - anti-virus software (free)
* MacScan - spyware scanner (not free)
* Yasu/Onyx - OS X maintenance/optimization tool (free)
* HandBrake - software to rip DVDs into different formats (free)
* VLC - media player (free)
Some sites with free software lists:
http://www.opensourcemac.org/
http://alej745.tripod.com/grassknucklers/Blank.html
http://macs.about.com/od/softwareand...p_freeware.htm
http://www.emmaalvarez.com/2007/11/t...-free-and.html
Some sites you might want to keep an eye on:
www.macupdate.com
www.tuaw.com
Hope that helps...