We've taken a few looks at Algoriddim's excellent djay software before, originally for the Mac and introduced to both the iPhone and the iPad in the last year or so. And the excellent iPad version has just gotten better -- a free update brings the software to version 1.2, including compatibility for all of the processors in the newest version of Apple's tablet, making it faster than ever and providing for high-end features, such as time stretching, looping and advance audio analysis. The desktop version of djay can do things like detect beats in your favorite songs and sync tunes automatically, and now the iPad version of djay can do that as well (provided you're running it on an iPad 2).
There are also some updates for the first iPad model, so you should still grab the update when possible. Algoriddim's djay for iPad software is US$19.99, but that's a solid price for all of the features an app like this provides. With these new features, the iPad version of the app provides almost everything the full desktop version does in a much more portable package.