So, what favorite nifty items have you or your DMs ever come up with?
I wanted a resource mage loosely based off of Humphrey (from Piers Anthony's Xanth series), but young and happy. My DM came up with an item called "Bottles of Storage." Each bottle contains up to 300lbs of one specific item (i.e. one longsword, never two, up to 300 pounds of rocks, but only one type of rocks, one 50' silk rope, but not two unconnected ropes). Anything can be put in the bottles as long as I can physically manipulate the object (meaning, hold it or move it. Whereas I might have trouble lifting up a rowboat, I can at least maneuver it enough to, say, stand it on its end, which is enough to be able to put it in one of these) and as long as it was never sentient or magically animate. I can't stuff a person, a dead body, or a construct into it, among other things. I can retrieve the item from the bottle as a standard action (not counting actually retrieving the bottle), and the item appears either in my hand or safely near me. Therefore, I can't bottle 300lbs worth of water then shoot it back out at someone, and anything put in the bottle will come out in its entirety all at once, so I couldn't just get one drink's worth of water out, I'd have to remove all 300lbs at one time.
One of the best things about the bottles is that if I cast a spell on something then put it in the bottle, the spell's duration does not expire. Therefore, if I wanted to "Shrink Item" on, say, sailing ship (if this were possible), and get it to under 300 lbs and maneuverable, I could stick it in a bottle and save it for later.
They were extremely expensive, but I still bought 20 of them (yay for starting gold for PCs about 1st level!).