I can't say I'm really a fan of the name, but Radballs is a solid music puzzle app for iOS that reminds me a lot of Lumines (definitely not a bad thing). You need to match up little orbs in sets of 4 or more to make rounded-off rectangles, and then, just like in Lumines, a "beat bar" comes by to clear them off the board and earn you points.
You can grab the beat bar to "scratch" it for extra points, or use powerups as they drop to help you clear the board as well. The music is well-done (there are even some OK Go remixes in there) and ties into the gameplay very nicely, so you can listen and sort of make music as you play along.
It's fun and fairly addictive, though things are even a little complicated -- the tutorial is quite long, actually. The controls take a little getting used to as well; the balls will bounce around quite a bit, sometimes making precision moves tough to do.
Still, it's a good game -- if only that name was different. Radballs is a universal app for the iPad and iPhone that's US$2.99 on the App Store right now.