You can do lots of things with Gecko adapters!
I personally use USB Gecko which is better and really easy to transfer backups and gamecube saves to pc. Got it from
[Only Registered Users Can See Links. Click Here To Register]
They offer nice price with worldwide shipping and have in stock both SD Gecko and USB Gecko.
What can you do with SD Gecko? I think the proper question would be what can't you do with it?
You can:
-Play emulators with roms and saves stored in the SD card:
[Only Registered Users Can See Links. Click Here To Register]
Which emulators? Atari, NES, SNES, Master System, Game Gear, Genesis, GameBoy- GB Color- GBA, Scumm, PCE, Neo Geo Pocket, Neo Geo CD, MAME, Nintendo 64, etc
-Play GameCube backups stored in SD cards:
[Only Registered Users Can See Links. Click Here To Register]
-Play homebrew games and other scene applications as bioses
-Manage saves to pc (though this fails sometimes):
[Only Registered Users Can See Links. Click Here To Register]
-Rip backups:
[Only Registered Users Can See Links. Click Here To Register]
etc
You can use Gecko products with a moded GameCube or a moded Wii.
You can also use them with an unmoded GC/Wii through SD Gecko + Action Replay method:
[Only Registered Users Can See Links. Click Here To Register]
And seems that is in the work a way to play them on Wii only with the aid of an original Zelda disc.