Okay, memory materials.
In SR, the only thing I've seen is the Nanopaste Disguise kit, which is totally awesome by the way, allowing you to create a realistic disguise with multiple preset configurations and do some crazy Mission:Impossible-style impersonations (because really, latex masks? pfft).
But there are other times when you might want to have something turn into something else, you know? Like turning your belt into a ninja sword (just take it off first) ... or a gun even? Why should monowhips be the only ultra-concealable weapon? I mean, they're great and all but sometimes you just want something else.