Here’s the scenario: You have a thousand MP3 music files sitting on your home computer—which is great when you’re actually sitting at your computer but a lot less useful when you’re in the kitchen or living room. What you need is a dedicated device in another room that can pull songs wirelessly from your PC’s music library and play them through its own speakers. Several off-the-shelf products can handle this task, such as Logitech’s Squeezebox; unfortunately, they start at around $300.