There are several sites that have Texas maps with the towns listed, including MapQuest and Geology. The types of maps vary from static photos, to more interactive maps that include a zooming feature to increase the number of towns viewable as you zoom in.
Interactive maps, like on MapQuest, allow for zooming in on specific areas of the state and moving around as needed. These maps can also be set up to show the hotel, restaurant and entertainment options in the area. These types of maps are best for people who are planning trips or need to know distances between locations. There are also options for directions on some of the interactive maps as well.