On the Republican side, it appears that former Senator and actor Fred Dalton Thompson may be testing the waters for a presidential run.
America once elected a president whose resume included stints as an elected official, an actor and a radio commentator - twice, actually, the second time in a landslide. It's not impossible that they could have the chance to do so again.
(H/T Bill Hobbs)
UPDATE: We can now add the name of Hillary Clinton to those candidates seeking the 2008 nomination.