A thread at SEO Chat forums named Name That Filter is fun. You know how SEOs often come up with different names for the various changes taking place in the SERPs for particular sites. I have mentioned many types of filters here in the past. Here are some of the filter names mentioned in the thread.
1) Trust Filter 2) An Aged Link Filter 3) An Affiliate Filter 4) Rapid Content Filter 5) Rapid links filter 6) Missing elements filter 7) Exchange filter 8) Duplicate Content Filter 9) Domain Name Registration Filter 10) Internet Protocol Filter 11) Adult Content Filter 12) W3C Compliance Filter 13) Disabilities Filter 14) Slow Load Filter 15) Duplicate Content Filter 16) Bad Backlinks Filter 17) Outbound Links Filter 18) Length-Of-Time-Between-Updates Filter 19) Geography Filter (Country Search) 20) File Type Filter 21) Language Filter 22) Content/Keywords Filter
Here are some I discussed in the past, not all necessarily "filters."
23) 'Omitted Results' Filter 24) Country Specific Filters 25) The Network Filter 26) The Hyphen Filter
Fun...