When I first browsed the Arduino site I am sure I saw a repository for designs. I can find the software library share but not the hardware share.
I have used an Atmega 328 and Arduino to build a chicken coop pop-hole opener. The design is based on the Arduino with motor shield but includes a current measurement facility which might be useful to others. It uses a Light Dependant Resistor to measure light levels and works out what the season is and what the time of day is to open and close 4 pop-holes at appropriate times.
The design is released under GPLv3 and it, along with the research notes are posted at www.electrichen.co.uk.
You can post projects on the playground - Arduino Playground - HomePage - you should have access with your current name/password. Have a look how others did it to get a feeling. When I place an article on the playground, I notice people on the forum and use the same thread to discuss the article/library
Thanks for the links. I found the page that says "This is the place to post and share your own code, circuit diagrams, tutorials...." and I think the current monitoring circuit should go under interfacing with hardware. When I have time I will add it there.
However, I can't see anywhere that has links to complete projects like my pop-hole opener. Perhaps there isn't one.