We were fairly impressed with the iRig Mix when we checked it out at CES — it's a portable DJ mixer that lets you connect two iOS devices (or otherwise) via stereo inputs. It was originally set to be released in February, but after a few months' delay IK Multimedia has announced that the mixer is shipping now for $99.99.
Of course, there are a lot of DJ apps out for iPads already, but using a single iOS device means that you have to either output through mono or cue your tunes without headphones. The iRig Mix makes things more akin to traditional DJing, with hardware sliders and knobs for crossfading, EQ, and other settings. You can also use the mixer with four free apps that work with hardware buttons for features like automatic beatmatching. It's unlikely to convince anyone to give up their Technics setup, but it probably beats plugging a phone into your stereo.