Spamihilator looks interesting. I know SpamBayes goes beyond the original bayesian methods developed by Paul Graham, but I'm not sure what else it does. I'll have to do some research. Do you use any of the plugins Merc?
The following are a few I picked out as most likely to be useful:
Blacklist Filter.
--Self explanatory.
RFC Validator
--Demands e-mails conform to RFC standards.
AlphabetSoup Filter
--Rejects e-mails w/ random strings of characters designed to confuse bayesian filters.
Scripts Filter
--Rejects e-mails containing embedded HTML scripts.
Domain Filter
--Rejects e-mails w/ funky domain names.
Mystic Characters
--Rejects e-mails w/ special characters in the subject designed to confuse bayesian filters.
No Comments Filter
--Rejects e-mails with HTML comments, another technique used to confuse bayesian filters.