Permit select users access to the owner's private galleries

I'm wondering if there's an easy(ish) way to permit the owner of a gallery to permit other users that the owner chooses access to private galleries. I can think of two ways of doing this from an interface standpoint:

1. Attach a password to a private gallery that the owner can then supply to any user the owner chooses.
2. The owner flags the users who will have access to the private gallery or galleries.

I could really use this feature. I'm not really a php programmer, so not quite sure how to tackle this...

shawn