I've knitted several pair of these. Not my favorite slippers, because I like to keep my ankles warm as well, but great for traveling. If I happen to leave them somewhere, I won't cry about it, as it is easy to whip up another pair in an hour or two. There are several free patterns out there, and they are all pretty much alike. Here's one

Here is a link that might be useful: Pocketbook Slippers

Would these be warm? My feet are always cold. Maybe use wool?