As a backpacker, I use instant coffee when I feel like having a cup on the trail. The little instant packs aren't half bad, especially when you have caffeine withdrawal and are out in the woods on a multi-day trip.
When I am car camping or canoe camping, I have a French press from GSI which is awesome. It is made from rugged lexan and is very easy to use; however, as with all French presses, cleanup can be interesting.
Another one to looks at, if size and weight is an issue, is the Primus / Brunton Flip and Drip coffee maker. Very few moving parts and very easy to use, but it only makes one delicious cup at a time. I bought one of these for a friend of mine and it works awesome.
If size and weight isn't an issue, check out Coleman's drip coffee maker that mounts on your two-burner stove. Also, if size and weight isn't an issue, and you want something really cool - check out the propane-powered Primus Brewfire.