Those who use Zotero 2.0 to manage their research and bibliographic citations may be interested in the collaborative group library I've set up for us. Anyone can click through and view items in the library, but to get the most out of it, and to contribute items of your own, you will need to set up a Zotero profile and be using Zotero 2.0. If you're not familiar with it, Zotero is a free add-on to the Firefox web browser. It is a bibliographic tool (like Endnote but free) designed by and for academics (George Mason University & the Mellon Foundation). I highly recommend it.
I have started the group library by adding several items, but I have not systematically gone through my library for every horse-related source, so the results are still a little eclectic. I'm eager to see what sources others might be able to add.