... without having to go through the boredom of stair-hopping the Infinite Dungeon.

I usually take any spell-casting capable characters in there, and come out with some decent low-level spells: Magic Missile, Burning Hands, Light/Darkness, and other spells of that sort. It's handy if you're playing as a Necromancer, too, the extra spells in the early game can make it much easier to get to the mid-game.

I mention this because it's not mentioned in any other source (like the Guidebook), as far as I can see.