I have been doing some research and it seems as though Madden 06 is not supported with xbc. Are there any other free options that will allow me to get online with Madden 06?

u obviously didn't do much research into the subject or you would know that only games with system link are compatible with the free online services available for the xbox ..

It's less of Xlink, Gamespy, and XBConnect that support the game, it's the game that doesnt support those tunnels because of the lack of System Link, the reason the games that are compatible work is because they are all system link (ie made for direct xbox to xbox connection)