Paul White from Sound on Sound has written a starter article on building your own Piezo drum triggers. Check out the words of wisdom at BEAT THE SYSTEM

This link has little promos for the Roland V-Drums: The Pro's Choice the click on the RT-20 triggers.

In amongst the hype to sell the product, there are some interesting jewles of professional advice. Mark Schulman the drummer for Pink etc.. talks about how he gets that huge live gig sound augmenting his drums with triggers. Work your way past the hype and see what they have to say - I think it is worth it on a few occassions.

The Roland - SPD-S: Sampling Pad is the latest version of the Octopad - this time with 9 pads in 3 rows of 3, with the top 3 really looking like they were intended for cymbal triggering. The Roland site has a very good demo video by Johhny Rabb on sampling with the SPS-S; he uses it in a number of different ways and I think underlines that depth of experimentation and knowledge of possibilities leads to really interesting (you might not like his music, but he sure does do some cool stuff) outcomes, and really works the potential of the technology. Music Technology is mostly used at it's most simple level, so check out the video....
Roland also have some hand percussion controllers and a trigger to MIDI interface

I have no involvement with the Roland company.

we have all experimented with Piezo drum triggers, taking the amplitude trigger from the littl piezo taped to the drum skin and using that to trigger samples - electronic drum sounds or what ever else takes your fancy. Well ddrum have some high quality Acoustic Drums Triggers which have rave reviews and can be adapted to any exisitng acoustic drum. Worth checking out.....

This is an extensive list of adaptors to allow Game Controllers to connect to a computer - making it available in Max/MSP etc.

Some particular ones that work with the HI object in Max are:

Super Dual Box Pro
Trio Linker Plus
Make your PS2 controllers Wireless

An Interesting Key interface is the laser-x-warrior-fps-gaming-keypad

STEIM have been working on interfacing games controllers using USB for a while and their JunXion software is excellent allowing you to make anything into MIDI and redirect it.

If you have experience doing this please add some comments - share your thoughts

The MAKE Controller Kit consists of the Make Controller Board and Make Application Board and can be used in a variety of different ways, including:

Poly Mode: Several simple functions are available by configuring the switch on the board - no programming required. To get this mode working, upload the Heavy bin file into the kit using the MC Helper application.

Stand Alone Mode: Write code for the Controller, and load it onto the board. A large and growing library is available to make this easier. To start programming in this mode, download the toolchain, the code base and the MC Helper application. Consult the API here.

Connected Mode: The board can also act as an interface between your computer and sensors and actuators. The computer communicates with the board either via USB or Ethernet using the very popular OSC protocol. OSC libraries exist for most programming environments including, Max/MSP, Adobe Flash, Supercollider, Pd, Processing, Java, Matlab, PHP, C and C++ and others.

Max/MSP uses OSC to talk to the board so there is a lot of support out there

A couple of years ago, Making Things launched an innovative range of modular sensing based system called TELEO. The operate on a network so are easilly extensible, and they have a range of boards to drive different kinds of outputs or accept differing inputs including various motors

You can find the user guide here

I think their tutorial documents are some of the clearest on offer

This looks like a VERY COOL way to learn something about electronics. The Snap Circuits Electronic Educational Kits have a wide range of components that simply snap together like lego - so wiring, no solder etc

Tracking movement can be difficult and usually requires video tracking solutions, however it is possible to use Thermal Array Sensors

Other options include the 442-3 IR-EYE Integrated Sensor , which is a Lithium Tantalate pyroelectric parallel opposed dual element high gain detector with complete integral analog signal processing. This unit offers greatly improved detection capability over an extended temperature range of -40 to +70 degrees C. with no significant change in noise or sensitivity and significantly reduced temperature spiking.

The BlueSense - BlueMelon provides wireless connections for digital and analogue I/O and some nice boards for driving servos and DC motors