One of the companies that is finally putting the GC-GBA link-cable to good use is Ubi Soft in their upcoming multi-platform title Rayman 3: Hoodlum Havoc.
Features included when hooked up:
Nintendo's David Gosen stated: "Ubi Soft has really explored the opportunities of extended creativity that linking the Game Boy Advance and Nintendo GameCube together offers, and we look forward to seeing more examples of this unique offering."
The GameCube and Game Boy Advance versions of the game are released on the 21st February, 2003.
Below are the some screenshots:
[Source: Games Asylum]