Like ppine says, resinous woods like pine or juniper. This is where your most valuable tool comes in, the knife. You need a blade that takes a very fine edge and holds it well. Shave paper thin curls off of your chosen dry wood. These will take a spark into flame quickly. Experiment with your local materials. This is easy to do in your backyard and a good place to hone your skills. I see other good ideas and materials on this thread.
Blind Horse makes a good little knife for this, their amazing little Bushbaby. It is full flat ground with a very thin edge. Here it is next to a SAK Farmer for size. The blade steel is 01, good carbon steel.
Also look for a knife with a Scandinavian edge, or as they call it, a scandi edge. A lot of the high end Scandinavian knives are expensive, especially now that the Euro is so expensive. About 8 or 9 years ago I sent off to a place in Finland and got the materials to assemble my own for 20 bucks. Prices have most likely gone up and I think now one can find most of this stuff in the US. The beautiful wood, the extreme curly birch is becoming much harder to find but you can use other woods too. The blade I used is a Lauri carbon blade and I made the nickel silver bolsters with a piece of stock I got from the guy in Finland as well. In the winter I use this knife every day right here at home. It has become perhaps my most favorite knife for fire making.
A smaller version is great for taking along in a pack but you can get a lot of knives to work for you if they will take a good edge and hold it sufficiently well. I prefer a strong, light fixed blade as I have had a large, tough Al Mar SERE folder fail on me at a costly time at 10,000' in an intense storm.
So, get a good knife and almost anything is tinder. You can shred bark real fine or most any kind of wood. Again dry, soft, resinous woods are superb for taking a spark to flame. Experiment, experiment, experiment.