Brainwallet is a program that takes a passphrase (hopefully a good one) and deterministically creates a Bitcoin wallet. This wallet can be used for transactions, then deleted from the computer. To get access to the wallet again, one only needs the passphrase to recreate it.
Does something similar exist for GPG?
If yes, where can I get it?
If not, is it even possible to create such a program? Maybe it's just a bad idea?