Samplr is a modestly-named app for sample and loop manipulation, notable for making superb use of the iPad's multi-touch surface to stretch, transpose, play and twist up to six samples.
The iPolysix app faithfully recreates the original synth's architecture, which had six VCOs, one for each of its six voices. Does it do the original justice?
iTrack Solo is Focusrite's first audio interface designed for use with iOS devices, although it can also be used with a computer via its USB 2 connection.
The iO Dock from Alesis is designed specifically with the iPad in mind and offers a pair of 'combi'-style audio inputs, MIDI DIN and MIDI USB plus a handy footswitch socket.
SoundCloud is a web-based tool for digital musicians to streamline the process of hosting and distributing audio. It simplifies and optimises the previously laborious process of moving music on the web, allowing users to effortlessly upload tracks and share them anywhere on the web.