I have always wanted to design, build (read: have somebody build), and live in an octagonal house. In 2002, I sat down with a basic vector drawing program and designed one.
However, that original design didn’t age well. When I started reevaluating it I realized that I hadn’t defined any sizes, certain things just wouldn’t work, and so on. So, in the early days of 2005, I redid my plan mostly from scratch (though the new one has many of the same features as the first) and in a more flexible format. The result is a large, pleasantly organized single-family home well suited to Melissa’s and my needs with plenty of flexibility for any additional future family members, guests, and so on.
Three-Wing Octagonal House (PDF).
In addition to what you see in the above PDF, I have some interesting technical plans. Being a nerd, the house will be very, very high-tech—high speed business-class networking (wired & wireless), power redundancy through line power augmented with solar and/or wind power, steel frame for protection from earthquakes and hurricanes and other disasters, and more.
Should be expensive ;-).