Black anodyne dyes that are available for woodworkers are great for the framer as well. Final finish - paste wax. You get a wonderful, and renewable satin glow. I frame all my own painting and this combination always gets people asking where I bought the frame.

For woods that I wish to leave "natural" I use Watco oil or Waterlox finish. Just coat, wait 20 minutes and wipe off. The more coats you put on, the shinier the wood gets, but it's never really high gloss. Paste wax is good here as well, since the surface can be buffed after all is put together and fingerprints removed. I use Butchers wax. Renaissance Wax or any of the other microcrystaline waxes are great for preserving things but I find them too hard for frame finish.