Playing as a warrior in Angband, I happened to find two (okay, more than two) rings of teleportation ... with the caveat that they increase my speed by +2 each.
This got me thinking about how I can use them as some sort of stragy. The best I came up with is equipping both and ripping through low levels to kill uniques and fill out empty equipment, but other than that, I got nothing.
At high levels, the random teleportation can easily mean instant death if you end up in the wrong place.