After several years of baking in North House Folk School
's wood-fired brick oven, I decided to build an oven of my own. I went a little crazy with extra features (slab foundation, arches, ash dump, chimney, doors, wood storage) and decorations (limestone around the foundation), but you can make a very usable version in a weekend with salvaged materials and a couple of friends.
The place to start is Kiko Denzer's "Build Your Own Earth Oven"
I also made extensive use of Daniel Wing and Alan Scott's "The Bread Builders"
, which is a great resource even if you're baking bread in a regular electric oven.