I love Ellen Ullman. While best known in some circles for her groundbreaking memoir Close to the Machine: Technophilia and its Discontents, about her life and work as a programmer, she's also got two great novels under her belt.
The first, The Bug, set in the mid-1980s, is about a programmer driven to madness by his inability to find and fix a bug in the code he's written. It's a great book, tense and insightful, reminiscent of Richard Powers' The Gold Bug Variations, not in the mere coincidence of the titles but in how each author elegantly charts a relationship between the human and the mathematical.
Ullman's more recent novel By Blood has nothing at all to do with technology—it follows a disgraced professor who surreptitiously eavesdrops on sessions between a psychiatrist and her lesbian patient, becoming ever-more involved in the problems of the patient's life, and by extension, with the gay subculture of San Francisco in the 1970s.
Salon just published a thorough overview of Ullman's work, which digs into all of the above and more—if you've never read her, this profile will probably convince you to give it a go.