Sealskinz....hmmmmm. I also find the neoprene ones to be fairly cumbersome. Especially if I have to carry them in my commuter trunk-bag to work. I have also thought about using plain old plastic bags. I especially like the idea of re-using grocery bags. I've not used them on a bicycle yet, but they have saved my feet a number of times in unexpected cold and wet conditions while hiking in the mountains. They don't breathe, but they keep your foot-wear warm and dry from the outside. Of course, my hiking shoes or boots also need a good airing and drying out after (from the sweat).