In addition to the Houston ISD databases available on the Research page of this site, try the links below.
Texas Indians :
The Alamo - site of the Daughters of the Republic of Texas
The Handbook of Texas Online - searchable database of the Texas State Historical Association and the University of Texas.
Lone Star Junction - a Texas history resource with archives of people, places, documents, events of early Texas, and a datbase of over 10,000 Texians. Voted one of Texas' best websites by Texas Monthly magazine.
Texas History Information - from Texas-On-Line includes flags of Texas and many other interesting facts.