By having a look at my site statistics, I noticed that many people were still looking for stuff related to one of the these two topics : Yeti3D, a portable 3D engine written by Derek Evans, and DevkitCube, a GCC build targeted for GameCube development. So here is some information about them :

• As you may have noticed, the official Yeti3D site has disappeared. Despite some attempts to contact Derek, I have no news about him, so I can't tell you what happened. Anyway, the GPL version of Yeti3D can still be downloaded here : Yeti3D GPL version. It contains the source that can be use to make a GBA build (and a Windows build, with DirectDraw or OpenGL support), as well as the level editor. Note that the GBA build process relies on an outdated toolchain (devkitadv), so a bit of work will be needed to use a newer toolchain here. I'd recommend devkitARM for this purpose. devkitARM is part of devkitPro, see below for more information.
  
  
• DevkitCube hasn't been updated for ages. However, some sites still link to it, and especially this Slashdot.org article. So if you're interested in GameCube development, please use devkitPro GCC builds and libraries instead. Note that according to the specifications of the upcoming Wii, the devkitPPC build might be suitable for it, when someone finds a way to run some "non-official" code on the Wii. devkitPPC (as well as devkitARM which is suitable for GBA, DS and GP32 development among others) can be installed thru the devkitPro installer. See devkitPro official site for more information.