The current go-to action/adventure stars these days are The Rock & Vin Diesel.
Nic Cage is hit or miss as he's not a steady action film guy.
Arnold is too busy being 'The Governator' to do movies anymore.
Stallone & Willis are trying to make a comeback to the action genre with new films coming out in 2007.
Van Damme & Seagal are mere shells of themselves with their new schtick direct-to-video action romps.......which are 50/50 - 50% terrible and 50% decent.
Seagal's weight gain and 'Crouching Tiger, Hidden Dragon'-like moves in his newer films really only serve to make him look foolish in those films.
Dolpg Lundgren is another direct-to-video actioner, but his films are usually quite entertaining.
IMHO, action film hot commodities fluctuate with the trends of the times. In a few years Rock & Vin may be outdate compared to whomever is coming up through the action film ranks behind them.
BTW - how come Wesley Snipes and Jet-Li didn't make this list?