GBA Tilt Cartridge
Though one might not expect it from a portable, the Gameboy Advance saw its share of alternative controllers, but in many cases, they were built directly into the cartridges. Boktai had its light sensor, and games like WarioWare: Twisted and Yoshi: Topsy Turvy made use of a tilt-sensing gyro. Nintendo also included the gyro in Kirby: Tilt 'n' Tumble, but the shipping version of the game was scaled back greatly in scope from its original concept.
Wii Prototype Specs: One Gamecube taped to a Gameboy Advance
This arcade architecture was used for several motion-sensing games, as well as traditionally-controlled ones. One that I'd seen in a few arcades, but never played (for fear of looking like a fool) was Tsurugi: The Sword. Gamers wishing to play out their saber-wielding Star Wars fantasies ought to seek out this cabinet if you can't wait any longer to unleash the Force. Other notables on the system were Mocap Boxing and Police 24/7. If you're a fan of any of those series, we'll gladly sign your petitions for Konami to port them to the Wii.
Many of us hardcore Wii Fanboys were once hardcore Dreamcast Fanboys. Our closets are filled with peripherals and game-enhancing gadgets that could now be summed up in functionality with a Wii Remote. Naturally, franchises like Sega Bass Fishing are now making their way to the Wii, but it may come as a surprise that its old fishing rod controller could be used for other games. The Dreamcast fishing rod featured an accelerometer, so that you're line casting motions and jerking motions would translate to the same action in-game. Because the rod remapped standard Dreamcast controller inputs, it could also be used in other games such as Virtua Tennis 2.
This alternative use was not advertised at the time, but had it been, the Wii might not have been looked at as such an original concept. Imagine how differently history may have unfolded if Sega would have played up motion-sensing controllers all those years ago.
Specs: Two Dreamcasts taped together
Another former Dreamcast exclusive now on its way to Wii, Samba de Amigo had maraca controllers that could detect in which direction they were being shaken. The upcoming Wii sequel looks to use the accelerometers in the Remote and Nunchuk to replicate those controllers, albeit without the tactile feedback of the beans rattling inside. Expect 3rd party controller add-ons soon after the game ships.
In addition to the SIXAXIS, GlovePIE .30 brought in support for the TrackIR head-tracking system. With the first version of the device having been released in 2001, the TrackIR method of head tracking beat Spielberg's to market by seven years! It works by placing an infrared camera on or near your screen, and an IR source on your person, in a reversed perspective to the Wiimote/Sensor Bar setup.
It's similar in concept to Johnny Chung Lee's Wii Desktop VR, and he may have taken inspiration from that product, given that he mentions others using IR LEDs mounted on the bill of a baseball cap, as is demonstrated in the TrackIR demonstration.
Not quite as exciting as exploding blox
No matter the inspirations of the Wii, its impact on gaming has been worth far greater than the sum of its parts. It really wasn't the controller that led to the early demise of the Dreamcast, so much as poor marketing, company mismanagement, and fierce competition. The unprecedented success of the Wii and the more cautious management means that we don't have to fear our beloved Wii being relegated to bargain bins and fire sales any time soon. It won't fall into obscurity and be that once-hot console you forgot about, only to be reminded of when watching re-runs of MTV Cribs.
But if by some extremely remote chance, it were to be end-of-lined sooner rather than later, what features would you like to see scavenged for use in the coming generations?