Multiple Non-Arbitrary File Uploads

Can anyone point me to a good way to have multiple non-arbitrary file uploads on Rails, possibly with a plugin? I came up with my own way using a single generic file upload model and single table inheritance, but I was wondering if there's a better way.

By non-arbitrary I mean each file upload has it's own purpose so I must be able to access it individually and it should have it's own validation rules.

Thanks in advance