My experience with automapping is that it is not so "automatic". Not to worry though. I am using a Novation X Station. I had it long before i started doing the controllerism stuff. If you are musically inclined then you might consider getting an X Station with 25 keys. You can set the thing to spit awesome arpeggiations that sync up with Ableton. The thing with Ableton (if that is indeed the software you will be using - you should anyway) is that you can map any MIDI function to any button, slider, knob, or even the cool touch surface on the Novation or its joystick for modulation/pitch bend. You simply activate Ableton's onscreen "MIDI" tab in the upper right corner, then you click on screen whatever function you want to operate externally, then you simply wiggle, turn, or press the slider, knob, or button you want to assign the function to. There is also a "key" button next to Ableton's MIDI button that allows you to assign keystrokes to functions. Ableton is the ultimate DJ/recording/looping tool - hands down! In my ten years of electronic music I had just learned the true power of Ableton Live nine months ago, and it is a customizable tool for performance - or recording I guess.
There are controllers out there that are made for Ableton, but make sure that whatever one you go with has a joystick or some other type of X-Y controller on it. Here are three products that will run all of Ableton's functions (aside from the ultimate tool - the X Station):
CME's Bitstream controller is thorough and even has a sequencer/arpeggiator in it.It runs $400.00. It automaps to Ableton.
Any of Faderfox's controllers are made for Ableton. You may need two or three different units, but they are small and are like $300.00 a piece.
Kenton makes a very small footprint item - All silver called the "Killamix" I believe. They just added a joystick to it. I'm not sure of the price - hold on...Good god! $500.00!! It is so little though. They have a lot of these items at analoguehaven.com. They tend to be a bit marked up on some items, but they are also cheaper than a lot of other places. They deal mainly in modular synthesizers.
Hop this helps. You can see our system as the profile picture at myspace.com/runninthingsrecords
Kipp