The Check Mii Out Channel (Mii Contest Channel) was a free Wii Channel for Mii sharing and contests:
Discontinued: WiiConnect24 ended June 2013. Wii Shop Channel closed January 2019. The channel is no longer downloadable, but remains functional for local Mii viewing/contest browsing if already installed.
Modern alternative: Mii creation/sharing via Nintendo Switch (Mii Maker, Nintendo Account profiles).