One of the things I’ve been working on recently is a sequencer/synthesizer for the iPhone called THUMP.
“Thump is the ultimate pocket groove box for your iPhone or iPod Touch. The intuitive interface allows you to dive in straight away to make music in seconds, then explore the wide array of options and settings to tweak your sound to perfection. Ideal as a musical sketch pad or a live performance tool.”
I wrote it in openFrameworks, so it cross compiles on the Mac, so you can download the Mac version here if you’d like to try it. iPhone and Windows versions coming soon. Almost everything totally cross-compiles between Mac and iPhone. It’s the future.