encrypted filesystem that can be mounted remotely?

[Anonymous <BigappleRemailer@bigapple.yi.org>]

I'd like to keep some of the data on my computer's hard drive
encrypted, but not necessarily all of it. But I also need to be able
to reboot the computer remotely and log into by SSH without the
encrypted FS mounted, then mount the encrypted partition in the SSH
session (from a trusted machine, of course) presumably by giving a
sort of mount command and entering the passphrase.

I've never used an encrypted FS before. Is what I want possible? What
encrypted FS supports this?

Thanks.