Do any of the cards that can be used to run DS games run/emulate GBA games. I first read somewhere that the M3 could but after more research i found that it was more likely a rebranded R4. So is there a Card that can do this?
No, the DS can't and never will be able to emulate the GBA. However, you can flash GBA ROMs to the EZ-Flash 3-in-1 from most slot-1 carts using a homebrew program. RTC isn't supported, but other than that compatibility is pretty good. http://www.dealextreme.com/details.dx/sku.2967~r.63849641
My buddy had a DS flash card thing (One in the DS slot and one in the GBA slot) and he had NES, SNES, Genesis, GBA, and NDS running off of it. I think it was something like a DS Real. NOTE: They weren't two seperate things. The two cartridges relied on each other. The GBA is where the flash card went and I have no clue what the top one was for. For people who thought it was two different systems. NOTE 2: I just texted him. Its the Super Card and Super Key combo. Im not sure if I'm allowed to link though. I will, if its not allowed and a mod removes it PM me. http://www.ps2cover.com/supercard-sd-superkey-combo.shtml
3-in-1 + ExpLoader is the way to go with those cards. Even better option would be Cyclo DS Evolution with fresh firmware that supports 3-in-1 directly!