I was thinking about this today. I am currently enjoying all sorts of homebrew stuff on my DS (Mp3 playback, homebrew games, applications and so on) due to the fact that I flashed my DS firmware.
I have the ability to flash any DS (new firmware and old) as I have the passme and passme2 devices and the software needed to do it. I flashed two units for myself (one for abuse, one for backup) and about 10 others for friends in the area.
I noticed some folks talking about how they want to get into the DS homebrew/emulation scene, but don't want to go the route to flash their DS. You would have to get ahold of a passme (or passme2) and then take the flashing risk. It is really not all that difficult, but I can see how some may not want to do it themselves. Not to mention a passme2 would run you $28 before even performing the task.
Now I am thinking of providing a service in which I will do this for people. Send your DS to me for a fee plus shipping, and you will have it returned flashed and ready to go.
How many people would be interested in something like this? I am not creating a business out of it, but I would really like to see more people in the scene so to speak. The homebrew scene is really moving along. Someone has just ported Dragon's Lair to the unit (first 4 levels) and it is pretty awesome. Not to mention the SNES and NES emulators. I'm sure mroe great homebrew is to come and I need more people to talk to about it!