ooh, good topic.
I just discovered vinegar + steel. just pop a wad of steel wool in some white vinegar, wait a couple days and you have a nice grey stain that makes white woods look weathered- like the grey color of old cedar shingles, sometimes produces a reddish grey- don't know why yet.... This stain darkens with exposure to sunlight and with age...
Josh, and others mention charcoal stain- what's that?
in the photo, from top to bottom
sitka spruce stained (all these had a couple coats)
sitka spruce unstained
vine maple and braintan stained
vine maple, part with "regular" minwax type stain and part no stain.