You haven't made good use of your Arduino until you have it controlling your half-million dollar vehicle.

http://www.arduino.cc/cgi-bin/yabb2/YaBB.pl?num=1254445743

Pretty poor showing of projects to be honest. My entry for coolest Arduino project ( which was notably absent from that list ) : http://reprap.org/wiki/Main_Page .

Luck would have it I ordered the Uno and it is due in my hands today. Plan on making a hot/dry bulb thermometer for smoking meat in my BBQ kettle. Then moving on to a PID for Sous Vide!

The guy who wrote the PID library for the Arduino is about to release an open hardware PID controller, if you're interested: http://brettbeauregard.com/blog/2011/09/a-little-teaser/ I met him a few weeks ago at a hackerspace in Boston-- the thing looked pretty cool.

(On the other hand, maybe buying a controller would take all the fun out of it!)

Wow that looks shiny. Yeah making my own is part of the fun.

Update: It arrived! http://instagr.am/p/WRPUI/

...This doesn't quite qualify as an Arduino project.

Linus Akesson's "EuroDemo" efforts are NOT Arduino based - they are actually less than an Arduino electronically but still AVR based.

This is an old link but I think Linus's efforts still take the cake: http://www.linusakesson.net/scene/craft/

How about a live controllable RC car with camera? http://www.sfrover.com

I found the Silencing Celebs with Arduino to be the most interesting of the lot from a gateway technology point of view. Also following the link for this project further eventually led me to a very cool site, http://www.ladyada.net/.

The guy who did the uberfridge project posted it on reddit a few days ago, where he also answered a few questions

Link: http://www.reddit.com/r/programming/comments/mkgek/i_program...

Humbly submitted for consideration: <http://www.youtube.com/watch?v=m-0Zj8fJz8U>;

Controlling a squeezebox using RFID coasters and an Arduino.

Is it just me or does embedded unseparated ads automatically set off the spam spider sense?