Neoprene booties. Lycra booties will help some, but nothing beats neoprene. You can still use your clipless pedal and walk as normally as you currently do in whatever shoes you use, but cold and wet are severly limited. So much so in fact that I am looking for neoprene-backed gloves.

Tip: In really cold weather you can drop one of the hand warmer packs in the toe area of your shoe as well. They seem to work well for an hour or so.