The list is near endless Phil. I'll shoot some suggestions I'd use as openers for stage shows, and then some for table entertainment, let you go from there.
Koran's Medallion (Jermay version - used in gambling themed show)
Chair prediction (say Banachek's four seats three specs from Pre-Thoughts)
Dead of Night (Nyman)
Chance in a Million (sort of original, caculator used to find answer to random sum, prediction in full view from start of show matches perfectly)
Graffitti (Sankey, but given more of a mentalism twist)
Quick CT routine (various sources)
Force/reveal (various sources, make one up)
There's plenty of ways to get yourself going in both situations, and no hard and fast rules to play by. However, I would say this; try to make your opener at a table quick, easy to follow but big hitting. Don't make it look like magic, make it look like mind reading, or psychology or what ever it is you play. No long winded scripts, difficult instructions or unclear outcomes, it wants to be BOSCH! and now you know I'm a mentalist. Force and reveal is awesome for this because of the thousands of ways you can do it; quick, quicker, slow, slower, Banachek hands, Brown psychology, Vulcan mind meld, the options are endless.
I'm writing an essay currently on routining, the hows and whys as I know and see them, and your point has made me think I'll include a short section specifically explaining openers.