What are some unusual uses of the MacBook trackpad?

Question

You know, the MacBook has such a beautiful trackpad. Are there applications that use its power for music-making, drawing, or anything else unusual?

Answer 1

In the "unusual" camp there's a program called Inklet that purports to turn your trackpad into a Wacom-like tablet. They also sell a special stylus and sketching software.

For music there's Trackpad Magic, which allows you to create music using trackpad for input, and djay, a DJ'ing app that lets you "scratch" records with your trackpad.

Answer 2

There is MultiTouchMIDI by Jeff Kaufman, a free software that translate pressure on the trackpad into MIDI signal.

You can then use a music software to translate this MIDI into audio.

It is then a good Idea to have an external mouse that can control the pointer. Check "Ignore Trackpad when Mouse is plugged in" under Universal Access, so the mouse holds still when you play music.

Answer 3

EDIT: I just now realized you meant software applications, not practical applications. Answering that question, there aren't any applications that I know of that have specific functionality built in for the gestures of the Magic Trackpad. There are lots of applications that allow for performing basic functions using trackpads, but nothing beyond basic scrolling and clicking gestures.

Original Answer:

I use my Magic Trackpad exclusively and have found the gestures to be the most useful. As a drawing tool (I'm a graphic designer) it is not good...get a tablet for that. I have configured my gestures so that they invoke various tools or perform specific actions like creating or deleting a layer. There are keyboard shortcuts to performs these tasks, but I find a motion gesture to be faster than contorting my fingers to hit Command+Ctrl+N, etc.

Some of my global actions include:

3-Finger Tip-Swipe Down: Launch Chrome
3-Finger Tip-Swipe Up: Launch Mail
3-Finger Tip-Swipe Right: Launch iTunes
3-Finger Swipe Down: (Command+W)
3-Finger Swipe Up: (Command+T) // for creating tabs in browsers
3-Finger Click-Swipe Down: (Command-Q)

4-Finger Swipe Up: Reveal Desktop
4-Finger Swipe Down: Expose
4-Finger Swipe Left/Right: Application Scrolling (Alt+Tab)

5-Finger Swipe Left/Right: Snap window left/right
5-Finger Swipe Up/Down: Maximize/center window