Most local phone companies in the United States offer what's commonly called "naked DSL," although the companies themselves don't tend to use that term. Simply put, it's DSL service without analog voice or a dial tone. It usually costs more than adding DSL to existing phone service, but less than the combination of both.
You'll find AT&T's "DSL Direct" here.
But you have other options. Cable companies provide Internet service with or without their selection of TV stations. And depending on where you live, there might be smaller, local companies offering DSL service (although these small providers are dependent on the phone company). Check your local yellow pages.