Syncing iMac and macbook?

Okay, so I bought a macbook, and it's great. But I'm not yet ready to give up on my nice iMac. So I keep running into problems of downloading mail or editing pictures on one of them, and not having the results on the other.

Is there any good way of syncing the two of them so that they always have the same content in selected directories? Apple's iSync program doesn't appear to be this extensive, and I don't have a .mac account.