I'm glad you like it, wolfeman. As far as triggering your own samples, you should absolutely check out
NitroTracker. It's made by the guy who built the DSMidiWifi library and program I used to create MIDI-Jammer.
It's basically a mostly-fully-functional MOD sequencer for the NDS. If you don't know about MOD files, they're basically like a MIDI file with samples contained within the file itself - so sequence data and samples rolled up into one. They're fairly common in games and chiptunes and whatnot.
In any case, this tracker is great. Not only can you load up .xm files and samples onto your device and play them, but it even goes as far as to allow you to record in your own samples on the go via the DS microphone. It's a great little tool. The latest release has a bunch of new features, some of which are still a bit buggy - but I'd absolutely recommend giving it a go.
I have fooled around a bit with the Wiimote in MIDI contexts - for example, I was using it as a Mod Wheel for a bit with a keyboard I use that doesn't have one. However, it's less functional for something like what I created, because you just don't have nearly the kind of resolution for tilt that you'd need for pitch control. Maybe the Wii Motion plus will change that a bit...
I'll check out your mp3 soon. I'm a bassist too - I'm finishing up at Berklee College of Music this Spring. If you're interested, take a look around my site - I have some performances up there (although mostly I have Film Scoring assignments).
In regards to the Mac files I bundled in, keep in mind that the "Run Me" file is an Applescript that I wrote for a very specific purpose. It basically opens up System Preferences on Mac OS X 10.4 and sets up your Airport card to host a wireless network that the DS can connect to, named "DS". Then you'd have to use a game with Wifi options to go in and change your DS's Wifi settings to connect to the network your computer is now hosting before you can use it.
I basically created it as a short-cut for me, but figured I'd share it anyway. It would probably be much easier if you and your DS were just configured to connect to the same wireless network in your home or whatever.
Anyway, I hope you enjoy!
-Andy