This page list all the Genny dumpers and flash cards which were made by people, not (HK) compagnies.

I currently know 9 of them

MCC (dumper & flash card)
MDreader (dumper)
MegadriveReader (dumper)
MoD's Sega CD Transfer Suite (dumper & mini flash card)
orgot-the-name (flash card)
Fonzie's flash card (flash card)
GameMedic (dumper & flash card)
CartDisk (dumper & flash card)
Cyan's ROM copier (dumper)

Coming soon, all the stuff I have on them, including schemantics and (old) softwares, no more available on the net for some of them.