One of the best cards (go ahead, sort them by rating) you can get for your mobile device is on sale today on Amazon as part of their daily Gold Box discount program. I'm talking about the 32GB Lexar Class 10 microSD card that comes with a handy reader that plugs right into a full-size USB port and reads your microSD cards like a champ.
The main reason I wanted to point out this sale was that I own this very card, which I bought from Amazon back in June of '11. Except, I bought it for $90.35, and even at that price didn't regret getting it one bit (though I am feeling just a little bitter today). It is fast, it has been very reliable so far, and it's got a ton of space for music, movies, games, and so on. It was why I finally kicked my trusty Nano to the corner and have 5 seasons of Seinfeld wherever I go.
Yesterday's price was $59.99, and after today's $20 Gold Box discount, the price is so good that I'm probably going to buy a few just for gifts. Heck, I'll stick one into my tablet as well, and I recommend you do too (but make sure you have a microSD slot first - not all devices have them *cough* Nexus *cough*).