Please share your experiences and reviews about NAS (Network-Attached Storage) below. In particular, rate their compatibility with Macs, OS X, iTunes, Time Machine, AppleTV, and other Apple-specific tools. The goal is for future users to be able to easily find the best Mac-compatible NAS appliance.

Rules:

• Use a single answer for each NAS (no duplicates, please).
• Vote (up or down) on any NAS you have experience with.

Also welcome: useful reference links, such as this one from xlr8yourmac.com.