I often use the small, round, clear feet made of silicon rubber, self-adhesive. It works suprisingly well; I have 4 feet on my cutting board in the kitchen, and they have never fallen off in about 4 years of washing, occasional bleaching, etc.
You can buy 'em anywhere (Zellers, hardware stores, Wall Mart, etc) 8 for about $2. Look in housewares or hardware.
They will come off if you don't clean the surface first; and you can knock them off (because they stick out a bit) if you're careless. Still, it's simple enough to replace one.