This project is backed by a very dedicated group of people. Simply the best choice for anyone wanting to create their own UO server. You can find out more from the RunUO Site and documentation and discussion at the RunUO Forums
Here’s an introduction from their website:
The RunUO project was founded in August of 2002 by Krrios and Ryan. The server started out simply as an application to test Krrios’s Ultima Online Client he was writing. It did basic packet work to allow him to simulate the EA Games server. The first notion of this program being successful came when we discovered how smooth the walking engine was. At the time no other emulator even had a close interpretation of the walking in your standard Ultima Online game. We decided if it was this easy to do walking how hard could the other aspects of the game be to complete?
Thus RunUO began. We quickly moved from walking and talking to the main skills having been implemented. In just over a year, 36 Beta releases with nearly 5,000 code changes or bug fixes. The RunUO team has delivered solid, stable releases to its community every time. How do we do this? We run a production shard that gets code updates before we release, therefore we test every piece of code before it goes into production and is released to the public. We live by the philosophy if we are going to send it out to you, we are going to use it also. We would never release something we weren’t comfortable running and this has proven to provide a solid release every time.