I've been updating the OP with all the suggestions I feel meet the following crieteria:
1) Widely used (have I seen multiple PCs, excluding myself, use it casually in conversation)
2) Meaning not self-evident
3) Usage not mostly restricted to an exclusive social group ('rinthis, nobility, etc)
4) No cursewords (there's already a helpfile for that, presumably this helpfile would link to it)
Basically I would like to have a help file that will enable a newbie to >point Allanak or Tuluk, walk into the tavern, and understand most conversations that would be held there. But encountering and learning new slang is an important part of both exploration and playing characters in new areas.
Admittedly every players' experience with what slang is common will differ, so I'd like to see a discussion on anything I'm leaving out you think qualifies, or if anything I've included shouldn't be on the list.