I'm actually kinda surprised the Six Degrees game wasn't already here, so let's just go ahead and start one! For those who don't know how it works, the rules are simple:
1. Pick any two movie actors.
2. Using movies that they've been in and costars they've had, connect the two in six movies or less. (My family always played it that you couldn't use TV shows, made-for-TV movies, or straight-to-video flicks. And since it's my thread, I'm setting that rule.)
Example: Ashton Kutcher to Bill Murray.
Ashton Kutcher was in Butterfly Effect with Amy Smart.
Amy Smart was in Road Trip with Tom Green.
Tom Green was in Charlie's Angels with Bill Murray.
That one only took three connections, but you can use up to six if you need 'em.
Also, I know there are a couple of search engines out there online that'll actually make the connections for you. Aside from the fact that they usually include TV shows, they're not in the spirit of the game. If you have to use one of them to come up with the answer, you probably shouldn't even try to play. Please don't use 'em.
All that said, I'll throw out the first pitch. I'll even lob an easy one out there for you:
Connect Jack Nicholson to Heath Ledger.