1. A blessed bag of holding (NetHack)
The bag of holding (or a similar idea) appears in lots of RPGS; I chose the NetHack variant, as it comes with fewer restrictions. Imagine: one bag and you put all the crap in it you want! I mean, of course it gets heavier—though I specified a blessed bag of holding because it doesn't weigh as much as a regular bag of holding—but think how easier life would still be. No more checked baggage on long trips, moving is no longer a hassle, no more worries about closet space...
A bag of holding was my first thought, and to be honest it would be so useful and awesome that I had a hard time coming up with four more...
2. Link's ocarina (Ocarina of Time)
I have to travel a lot—or rather, I'd like to—and so long as I got to decide where the "fast travel" options are, the Ocarina of Time would be so handy. Plus, you can travel through time with it! With this and a bag of holding, you basically have a much more reliable TARDIS.
3. Magic pants (The Boy With Gold Pants)
I ran this question by JV. Funnily enough, his first choice was also a bag of holding: nerds of a feather flock together, I guess! But his second answer, "Golden pants," was an answer I didn't understand at all.
"You know, like from the story. The boy finds pants and the pockets are always filled with gold?"
"Um, this must be a Swedish story..."
And it is: a children's book from 1967, to be exact. Young Mats Nilsson finds a pair of pants and the pockets never run out of money (bank notes, not gold, so JV had remembered a little bit incorrectly). I don't know the novel has ever been translated to English. I guess it's like a magical realism version of Blank Check or Richie Rich?
4. A magical anti-aging portrait (The Portrait of Dorian Gray)
So the moral of the story is that Dorian Gray is an asshole, I know, and that's why it ends so unhappily, but if I could get a magical portrait without selling my soul, I would be so down with that.
5. An "eating your words" feast (The Phantom Tollbooth)
So this one isn't an item, really. It's a magic inherent in the world of the Phantom Tollbooth. But if this magic could be distilled into an item, like a table or a plate or whatever, that would be the best thing ever. Imagine: never cooking again! All you have to do is name whatever it is you want to eat and it appears right in front of you, just as you described it!
What magical items would you want?