As reported by Dreamcast Live, fans have recently managed to bring the Sega Dreamcast title Daytona USA back online. This brings the total number of currently available online Dreamcast games up to 26 (a figure which also includes the recently-released Dreamcast homebrew Driving Strikers).
Daytona USA (or Daytona USA 2001 as it was called in both Japan and Europe) is a remake of both the Sega Saturn and Arcade classic Daytona USA and was specifically designed with the Sega Dreamcast in mind. It features additional courses, a new Championship mode, and bonus vehicles, as well as the ability to race online (in all editions except the PAL version).
Sega reportedly took the official servers for the game offline over two decades ago, but thanks to the hard work of coders in the Dreamcast community such as Ioncannon, Shuouma, and Xiden, it's now possible to experience the game online again using the most recent version of DreamPi DLE.
If you want to give it a go, you'll need to have access to the North American version of the game (as the Japanese version has yet to be restored) and will have to go through the somewhat involved process of getting your Dreamcast online. You'll find a tutorial on how to get connected here. You can also see some footage of the game in action below.