They're in the process of building a light rail from the Astrodome through the Med center into downtown. There *should* be one from downtown out to Katy, Sugarland, Galveston/Clearlake, Kingswood, and the airport and Woodlands.
However, our friend Tom Delay has consistently blocked all funding at the federal level for rail in Houston. He's a bit of an ass.
Perhaps I should turn him into a very small perl script.
We do have the buses, however, even if finding the schedules and routes can be a pita.
I remember a story from the early 90's about Southwest Airlines squashing a plan to build a high-speed rail between the big three Texas cities (San Antonio, Houston, Dallas), since traffic between those cities was a huge percentage of their business. Gotta love how the politicians are always looking out for their constituents.