I've got a job...

...and therefore insufficient time to pull off hacks like this:

This page is a list of mirrors to the various DS games Nintendo was broadcasting at E3 2005 to anyone who came by their booth with a DS. These games are distributed in .nds format, and can be multibooted to a DS via Firefly's wireless multiboot program if you have a compatible wifi card.

[ akkit.org/DS/E3 - DS at E3 2005 - and others! ]

Of course, maybe some of these folks hack for a living, but I can't determine how they'd make any money at this. Not only have they captured the DS demos that Nintendo had at E3 but they've linked up to "WiFiMe", which is a server and set of drivers to make your compatible WiFi card into a broadcast station for your DS.

And looking for a cheap easy WiFi card that is supported by this, I found the cute Buffalo USB "Key Fob" 802.11b/g [WLI-U2-KG54-AI] which is rather cheap, and tiny, and WiFilicious.

Update: My bad, props to Nick at 4 Color Rebellion.

Update: ChiefValue has a compatible card for just over $20.