Each year we do a large how to solder workshop putting about 120 people per day through assembling a simple led flasher. Thanks to the affordability of dirty pcbs, it's also a fundraiser for us.
The design and instructions are all on github at http://https://github.com/vhs/vhs-pcbs/tree/master/maker-faire-2013
The faire and hackspace got a good write up in a local paper at http://http://www.vancourier.com/community/hacking-into-the-mini-maker-faire-1.2279288