I like architecture that thinks beyond the ordinary while still trying maintain functionality.  Here are some interesting stairs designed by TAF – Gabriella Gustafson & Mattias Ståhlbom courtesy of http://hovercraftdoggy.com/.

My only question is how you could get this past most of the building inspectors I have dealt with.

UPDATE: Luc sent a comment and link to “miller’s stairs” (see comments) for tight spaces:  http://www.mier.be/realisaties/trap_1.html.  I think that early american houses had more ladders in tight spaces, at least in the appalachians and the ozarks.