Most of these ideas have been discussed before.
Voice chat: not that feasible, because the Wii games don't run under an OS like X360. The Wii Menu acts as a loader; when the game starts, it takes right over the CPU. Possibly a heavily hacked/homebrew IOS could implement something like this.
DS: We could, if we knew how to work the wifi hardware well enough, send Download Play broadcasts to a DS, but we'd have the same restrictions as doing it on a PC. The programs are signed, so you need to have FlashMe installed on the DS to be able to download homebrew. (You can send all the Nintendo demos you like though.) You can't simply erase a DS game card either; they're ROM chips. Basically, the Wii doesn't open up any new options for DS homebrew.
Games/saves from external media: I'm sure it's possible, but I don't think the mods here want it being discussed because it opens the doors to piracy. I don't know the system well enough to say much about it. Hacking games to save to SD/USB is possible, but would probably be difficult. All things considered, it's probably not worth the effort, since 512MB is plenty of space for saves and will hold a decent number of VC games; the only reason you'd want to use external memory at all is for backing them up and moving off the ones you're not currently using. Someone recently developed a SadMenu patch to remove the save game copy restrictions, so that will probably be in the next version of StarFall.
(Considering, though, that games probably all use the same routines from the devkit for saving, or pass the data to IOS, hacking them to save to SD might not be
that hard. Could be an interesting project.)
Edited 1 time(s). Last edit at 09/25/2008 02:42AM by HyperHacker.