Best thing I've found is stableicers. I tried yaktrax for a while, but they just didn't hold up, and they were prone to falling off.
This week has been HORRIBLE for ice at the barn! The paddocks are crazy icy. BO keeps sanding and sanding and sanding, but we're in this dreadful freeze-thaw-freeze cycle. The snow melted and made mud, which is also now frozen and thawing and freezing. There's only so much that sand can do, and salt just makes it worse, because it melts everything so when it freezes up again, it turns into a smooth sheet of ice.
I just leave a pair of duck shoes with the stableicers on them in the car. Huey has an easier time moving around on this frozen crud than I do. Much more of this, though, and I'm going to start having nightmares about him slipping on the ice and going down. :(