Aww, don't say that! You do beautiful horses; I couldn't even begin to figure out how to shade/highlight the way you do. (And anyway, if I were to win, I intend to offer breeding spots to other bidders if they want them.)
I just use the Flash from my Adobe CS3 package; I'd have loved to have a more recent version of Flash but I hate the newer versions of Photoshop/Illustrator so I make do. Honestly my favorite part is being able to incorporate some programming to either make the finished things interactable, or make the animations irregular (my next Flash project).