The Sorted Details: Folding Step Stool - Free Plan
Folding "Rathskeller" chair - Site has a lot of other ingenious projects as well.
An example of some simple, glueless joinery for large pieces that may need to be taken apart for transportation. Side note: make the ends flush to avoid leg injuries.
Japanese joinery, simple, functional... More Woodworking Projects on www.woodworkerz.com
Quattro Folding Adirondack Chair
Pawleys Island Folding Adirondack Chair
Prairie Leisure Aspen Folding Adirondack Chair