You love Yu-Gi-Oh right? Konami sure does. Every year they release an installment of Yu-Gi-Oh! GX Tag Force for the PSP. Yu-Gi-Oh! GX Tag Force 3 is scheduled to come out in Japan in the fall. North America should get monster dueling with the Duelist Genesis card set around the same time.
While Yu-Gi-Oh might not be for you or me, someone out there is buying the Yu-Gi-Oh! GX Tag Force games. Actually, make that someone(s) since Konami keeps developing more of them DS and PSP.