um. Lots of magic items (and magical locations) are designed this way. Just off the top of my head, from the WotC 3.0 Adventure Path: azan-gund (Sunless Citadel), the temporal-stasis altar (Heart of Nightfang Spire), the three thuribles (Deep Horizon).
From the SRD: the rings of elemental command, bags of tricks, eyes of doom, figurines of wondrous power, lyre of building, mirror of mental prowess. Rods of security, splendor, and thunder and lightning. Ring of shooting stars.
Lots of things measured on the week-scale. It makes things manageable. Frankly, I don't want my party's fighter throwing around flame strikes more often than that!
