JoMyFriendAtWork made a new graphics library for Dreamcast and PC programming which does basic 2d graphics using 3D hardware (giving ability to rotate, scale, ect). The library works on both PC (using SDL and OpenGL) and on the Dreamcast (using DMA PVR). He also made a clone of an old hockey game named hat trick and it runs very well from dcload-ip.

You can find out more, as well as get the downloads from this Consolevision forum post.