share & sync

ByteTaxi has recently been acquired by Microsoft. The service that used to cost $100/year is now free.

Shares folders across the Internet. Invite a different Foldershare user to share your folders.
Foldershare uses Spotlight, if the remote computer is running Tiger. Yes, it runs on Mac. And it runs on Windows.

Foldershare does not provide a relay service. Both computers need to be online at the same time to exchange files.

Check it out.