[mjn]

Texas also does as of a few years ago. In general services aren't taxed in Texas, but 17 classes of services are defined as taxable [1], ranging from movie-theater tickets to mobile-phone service to pest-control. One of those is data-processing services:

Examples of data processing include check preparation; accounts payable or receivable preparation; web hosting, web site creation and maintenance; data storage, including offsite backup of electronic files; conversion of data from one type of medium to another (i.e. converting paper documents or videotapes to digital files); and the performance of a totalisator service with the use of computational equipment required by the Texas Racing Act. Data processing services providers include sellers of software as a service and application service providers.

[1] http://www.window.state.tx.us/taxinfo/taxpubs/tx96_259.pdf