Technical "Books On Tape"?

Samrobb writes: "The company I work for has a fairly extensive in-house technical library, and they would like to expand to include audiobooks covering both general business topics (easy to find) and technology overviews (hard to find). Has anyone come across a company or companies that make it a point to deal in technical audiobooks? The few that we've been able to find so far have been rather unimpressive MCSE tutorials."