I know that there is an option to filter domains on the Raq email system but is it possible (with or without a package) to set up the type of filter that "dumps" emails with specific words in them?
The sort of spam filter available in CPanel is what I have in mind.

procmail is what will help you filter emails on your raq.

search this board for procmail, it's a little tricky but will do what you want.

You might want to search the SUN/Cobalt Solutions directory for the keywords Spam-Filter. It should turn something up if I'm not mistaken.

i believe spamcop has a pretty good filtering system.

i think there's even a howto in the rackshack forums for installing it.