Let me preface this by saying that while I have a lot of bandwidth, it is strictly limited. The GC and Wii streamed formats are very large, and I have a large collection of these files, so it is very easy for the site to go down when people decide they need to leech everything. Please restrict yourself to a few sets per day, or use some bandwidth limiting.
With that said, go to hcs64.com/bonus/Streams and have a look around. Files are organized by format, not by system, so you may have to look around a bit.
Regarding emulated DS music (streamed music is played with in_cube and just directly copied from the games), check out the manly 2sf archive. 2sf is a format like psf and usf. You'll want the vio2sf player, which can be found elsewhere.
There's a few programs that can create MIDI files from NDS games. The only one I know of is called VGMtrans, but I've never used it, so I don't know how good it is.
As for Sonic Rush et al., the problem is that although the game is probably rippable, the tools to do so are so poor that it's entirely impractical to rip the game right now. You're welcome to try of course, but Knurek (who's doing most of the ripping) isn't going to be ripping that one until someone improves the tools.
I hope that at least gave some useful information to you. Mouser X over and out.
The games I've come across when ripping 2SFs have all used MIDI sequences. If you use the 2sf RIP KIT on an NDS rom, then extract the contents of the .SDAT file, you'll get a load of .sseq files which can be happily converted to MIDI format. Stuff will be in the wrong registers and have incorrect instruments a lot of the time, but that is easy enough to fix - then you can probably convert from MIDI to XM.