I'm working on a personal photo album project (personal as in "for my use only") that kind of matches this. It took me a little under five hours to put together a simple rails site that lives on heroku, handles the uploads and thumbnailing and sticks the whole thing on S3, as well as handling display. Right now the only metadata is "name" and "description" but it's just a postgres database, you can add whatever you want.
Here's the basic app if you want to poke around. There's almost literally nothing to it:
Here's the basic app if you want to poke around. There's almost literally nothing to it:
https://github.com/peterkeen/phytos