I put online 6 extra terrains that you can add to your RoR install. Theses terrains are preliminary and does not include roads or buildings, but are fun to discover anyway. You can find them in the download section.
The next version of RoR is in progress, but not yet ready. It will feature a semi truck, and several optimization, including a multithreaded mode for Hyperthreaded (HT) and dual core CPUs!