Gamers Graveyard writes, "the XBAND idea is simple: create a network, accessed by a console system with a modem, and allow players anywhere to compete against each other. The Network was first tested in San Francisco, Atlanta, Dallas, NY and LA around May of 1995, and then went national later on."
"The XBAND modem was available for the SNES and Genesis, which you used to connect to the XBAND Network. The modem sold for an amazingly low $19.95! To get on the XBAND Network, it cost $4.95 for 50 "connections" a month, which were the number of times the network connected you to another gamer in your local telephone area who wanted to challenge you. Or, for $9.95, you had unlimited local connections. You could even play gamers long distance for only $3.95 an hour, anywhere in the continental US, which is about half of what a similar long distance telephone call would cost."
"The XBAND modem is, essencially, a blue/grey oversized SNES cartridge. It plugs into the cartridge slot on the SNES. On top of the modem is a slot where you insert the cartridge you want to use with the network. The phone line plugs into the side; the optional keyboard connects to the second controller port on the SNES."
"One of the most popular features of the XBAND Network was the ability to send and receive Internet email, or x-mail, as they called it. Only problem was that you had to type your x-mail on an on-screen keyboard, using a cursor moved with your game controller. Thankfully, there was a keyboard (or it could be used with a standard PC keyboard, I can't remember) released for the XBAND modem, which allowed you to to type x-mail messages. You could also receive two daily newsletters via x-mail; Bandwidth, which was a newsletter about gaming and related trends, and XBAND News, which told subscribers about all the lastest happenings with the XBAND Network."
"After a match, players can then "chat", using the same interface as the x-mail. Again, the keyboard, I am fairly sure, could be used to chat, also."
Read more after the jump. Also wikipedia has an XBAND page with specifics like "choosing 1 of 40 pre-set avatars".