Even though the Novation Launchpad was designed to control a specific DAW - Ableton Live -, it can be configured to work as a generic MIDI controller. With Lauflicht Stepsequencer from Cie, you can use it as a plugin for Renoise - a multi platform DAW for Mac, Windows and Linux.
With version 3.0 you can link multiple Launchpads together to create a monster GUI.
The full version is $29
Features in V3.0
Prototype alert, Karplus Strong in the house
Every flavour of distortion and compression ever needed to crush your signals
4 track performance sequencer for live performance