I vote thumbs down on prefixes.  I am now dealing with 400+ tables that all begin with TBL_XX_tablename, where XX is the initials of the guy who created it.  The idea is if you have any questions about the table, you can wander over to the Creator's cube and ask him (we have a rich oral tradition here).  Besides, if you can't tell its a table from reading the code, perhaps you should be in IT management...

I do practice the object-verb naming convention.  If you have a stored proc that adds a customer, call it CustomerAdd.  If you do it the otherway around, you have a bunch of procs that all line up in the treeview like

AddCustomer

AddThat

AddThis

when what you want is

CustomerAdd

CustomerDelete

CustomerUpdate.