There doesn't seem to be a forum here to just heap praise on the Arduino, but this one comes close for me.
I kept seeing stuff about this mysterious Arduino but even though I've done a few things with a Basic Stamp, I never really connected them in my mind....That is until I bought a Roomba, ostensibly to clean my floors.
After some unrelated difficulties with my old stamp, I decided to try the Arduino. Wow! What a step up! It's so fast and the C programming is so easy compared to dealing with all the limitations I had before.
It was easy to get the Arduino to control the Roomba, but not so easy for the Roomba to talk back. I finally solved it by putting a pair of inverters (4049) connected in series (like double ROT-13 encryption) between the data from the Roomba and pin 0 on the duemilenove.
Having gotten it all working, I got the Roomba to show its holiday spirit and play Jingle Bells. I'll get the video up in the Exhibition forum soon.
It's a wonderful product, I can't wait to dream up my first real project!