I bought the Atrix Lapdock since I couldn’t find any sub $100 portable HDMI displays. The only affordable displays I could find were USB only. With the Atrix Lapdock and some adapters, I was able to use it as a portable display for several devices, which is great for traveling.
It’s a good idea to remove the plate on the docking area (underneath where the phone would be). It makes it easier to plug in the adapters or have to sand/shave them less. You can easily pull it off with your finger nails (the plate actually has a couple of magnets to keep it in place, and two small plastic clips).
All high-res images used on this page are available here. Below are a few YouTube videos I posted about the Lapdock (the second shows that the Lapdock 500 isn’t “hacker-friendly”).