GCN Disc
The GameCube software is written on proprietary optical minidiscs, developed by Japanese Panasonic subsidiary, Matsushita. The advantage to optical media over compact disc is speed, allowing for faster, almost unnoticable load times in most games. The discs' diameter is 8 cm, while standard CDs and DVDs are 12 cm in diameter.
RETAIL: $20 - $55

Memory Card 59
The biggest difference between disc- and cartridge-based gaming is that you can't save onto the disc itself the way you could with cartridge games. So you have to have some seperate medium to save your files and data onto. Your future is in the cards. Nintendo's original units each hold only 4 megabits of memory in 59 "blocks". Certain games take up as little as 2 or 3 blocks, whereas others can occupy nearly an entire card, depending on how much and what type of information is being saved.
RETAIL: $15

Memory Card 251
Nintendo's decision to release such low-capacity memory units was certainly odd, since PS2's and X-Box's are at least 8 times larger, by comparison. Thankfully, there's the 251, which has since its release become the standard in GameCube Memory Cards.
RETAIL: $20

Memory Card 1019
For those of us with more extensive GameCube collections, Nintendo has recently released the 1019, which holds 4 times the ammount on a 251 for only $10 more. If you had problems saving all your files before, this baby can pretty much guarantee you will never again.
RETAIL: $30

SD Memory Card Adapter
With a bit of extra pocket change, Japanese gamers have been able to save their files onto one of today's more amazing marvels in technology, SD ("Secure Digital") Memory Cards. Smaller than your thumbprint and light as a paperclip, these wonders can hold anywhere from 8MB to several gigabytes of memory, and at least in Japan, they've become a common household storage item. The GameCube game Animal Crossing e+ (Japan only) uses this adapter to let you save photos of your accomplishments in the game, which you can then move via SD card onto your PC, where you can send them to friends over e-mail. Nifty stuff, although it didn't go far beyond that this generation. The Revolution uses SD cards in an entirely new way...
RETAIL: ¥1,500 (Japan only)