We had something like this at the old SS, so I thought I'd start a new one over here! I've compiled a whole bunch of unique, unusual horses to use as references. We've all hit a hexer's block at some point in time, so this is meant to help you out when you need it. Of course, feel free to add on to this, and I will be adding more as I find them. I have the pictures organized according to breed, just to make it slightly easier to navigate (I grouped them to the best of my ability, but some may not be the exact breed they're listed under).
Don't have any pictures off hand, but I absolutely LOVE this website for horses hexed for absolute detail. Most horse models shown have front, back, right, left, and close up photos. Rio Grande Horse Models