[Sneakerphile]

Goto your local hardware store or tool shop and get yourself a sparkplug brush. They usually look like a toothbrush, but they have a wooden handle and fine brass bristles. Tough enough to do the job, but not so rough that it'll fuck them up. That and the suede/nubuck cleaner from Kiwi as mentioned by MrSS.
I managed to get a 5 year old stain of motor oil out of the toe of a pair of tan suede kicks using this.