But you can validate and curate the uploads. In fact, that can be part of your community/crowd-source model, too. If someone else within your community comes along and rates/tags/categorizes the photograph, he can make a little slice of the pie.

Hell, get everyone involved in the process.

Solve chicken and egg problem first. Then maybe you can start thinking about cage-free organic eggs, second. ;)

I had considered this option, but it doesn't really fit with my current plan which is to focus on a specific niche which requires a certain level of quality.

I will be targeting flickr users though as there are some great guys on there, publishing awesome work just for the fun of it.