The one thing I find seriously lacking with Lua is the limited amount of libraries. However, there are some really good ones.
I'm curious about Lua Rings but I can't quite figure it out.
Certainly one of the more useful libraries is the file system library. That should make it very useful for shell scripting.
And yes! There is an interface to Toyko Tyrant!!
In fact, it looks like Lua is even integrated into Tokyo Tyrant!