As an alternative to tried and true audio editing and recording software, Ableton Live represents a fresh approach that is beloved by many musicians. Unfortunately, the software's unique grid layout of audio and MIDI clips is difficult to adapt to real-world hardware (many have tried).
Novation is really one of the first manufacturers to deliver a USB hardware interface for Ableton Live that makes sense. The LaunchPad ($199) automatically maps to Ableton Live and offers a bright, colorful grid of buttons that seasoned users will immediately relate to. Also, it just looks really cool.