Right now you can get Lemur on the app store for 50% off.
What can you do with Lemur? Just about anything – it’s an iOS control surface that sends bot MIDI and OSC, and includes an embedded scripting language for those of you who have serious itches to scratch. I designed a Lemur template for my Chroma sequencer and synth, which features bi-directional control (changes on the computer are reflected on the iPad and vice versa) – makes it a lot of fun to play:
Get Lemur here.
More info on Chroma here.