A great way to gently exfoliate skin is simple: use a washcloth. The fabric naturally rids face of excess oils, dirt and build-up. I don't use washcloths every day because I have to cart laundry two blocks away (oh, the joys of West Village living) and you don't want to re-use a washcloth too many times (my friend Laura keeps a stack of washcloths on hand and uses one a night -- good for her, bad for the environment). But I do treat myself with a warm washcloth every once in awhile (the warmer the washcloth, the more spa-like the cleansing). You can even get fancy with special peppermint oils. A quick nuke in the microwave and that scented washcloth will make you feel like you're in Sedona, Arizona, getting pampered for $1,000 a day.
See "How to Exfoliate" for more information.