I concur; TBAMud is a great way to get into coding/building for a mud. I have not looked around for other code bases all that much, but this seems to be the only one that is actively developed today.
Another plus side is you can do quite a lot with it. I am not sure what you had in mind, but I am sure that you can either find a snippet or create your own (with nice enough people on here willing to help, at least if you are willing to show you are doing your best). There are also a lot of awesome DG script references and examples on this site and forums.