Keep it simple with the Alesis Q88 USB MIDI Controller!

88-key Velocity-sensitive USB MIDI Keyboard Controller with Pitch and Modulation Wheels, Backlit Octave Up/Down Buttons, and Sustain Pedal Input, and Software

The Akai Professional LPK25 USB controller lets you get creative anywhere!

25-key USB Controller with 25 Velocity-sensitive Synth-action Keys, Arpeggiator, Sustain, Tap Tempo, 4 Programmable Memory Banks, and Editing Software - Mac/PC