Like a joint storage? Sounds pretty cool, but could raise concerns if someone misuses it (people sometimes break others' trust, it happens). I like the idea regardless, you'd just need to be extra careful about turning the option on.
Leaving stuff on the floor works too, but it also adds to load time a lot, so the ability to share SDBs would work better. +1!
You can set the prices to 1c, but there is no way to put stuff in.
If TS would implement SDB buy orders (the opposite of buying *from* a SDB, where you sell *in* to the SDB) would be really cool -- like for the co-op some folks are running