a bigger micro sd card for my 3ds, it has more room now! both my nds lite and 3ds have 32 GB of space in them. Not a lot but I think it's fine for me.
I've been wanting to jailbreak my flip phone so I also bought an extra, smaller SD card, but I don't think I'm getting anywhere with it... as cheap as this $20 flip phone is, it's stupidly hard to get into.