Not all magical and not all practical but I wish I them.
Owned by Lyra Belacqua in 'His Dark Materials' trilogy. You would have to learn how to read it but after that little problem, you can ask it anything! The possibilities could be endless.
The House of Mystery
The house from the Vertigo Comic series, 'House of Mystery' may be a large magical item but oh my this would be an amazing place to live. Plus, always an open door and other patrons pay with stories, entertainment and drinks, on the house.
Otherwise known as a universal translator, feeding off brain energy and giving you the ability to understand any language in the galaxy. This would be extremely usual in holiday. Down side, you have to shove it into your ear.
Quick Quotes Quill
This is the lazy side of me wanting this. Rita Skeeter may be a terrible person, but the quill that writes for you would be a great help, especially on the go.
Although this caused quite a bit of trouble for Sheeta and Pazu but the crystal is key to a floating city, a castle in the sky, plus you can fall from the sky and not die, just float with ease.
Bonus: Bernard's watch
Back in the 90's, I think everyone wanted Bernard's watch. It could stop and start time, that is all you need. Think of all the naps you could enjoy!