In reply to Jamming Dodger:
Kahtoolas are ace for off road and icy snowy conditions.
Yaktrax are better if you are likely to encounter roads too and dont want to keep taking them off.
You will see what I mean when looking at the two products. I have both and love them both for their relatively different applications. They are both comfortable and easy to use over trainers and trail/fell shoes.
Doubt the Yaktrax will last as long, but cheaper, and on sale I think with Go Outdoors right now.