To get rid of Spam I use PostArmor
http://www.postarmor.com
This downloads the headers of emails only. But it does need a LOT of tweaking.
A raelly useful utility is MenuMeters which I've had on the menu bar for over two years. It gives a constant readout in percentage of the CPU and a bar graph of memory. This enables me to spot problems with applications, websites, etc. really quickly.
http://www.ragingmenace.com/software/menumeters/
Onyx is really useful for doing regular Mac OS X system tidy ups.
http://www.titanium.free.fr/
Hope this helps.
Phil Cruse
http://www.colourphil.co.uk
