A few links that might be helpful:
http://www.atnf.csiro.au/people/Suzy...beginning.html
http://web.archive.org/web/200110060...ey/tubing.html
http://www.phred.org/~josh/build/suppliers.html
ftp://draco.acs.uci.edu/pub/rec.bicycles/frame.build (more on the process of building)
I'd advise just looking at the lug sets at Ceeway, Henry James, etc. If you don't know what geometry you want, check out the geometries of well regarded frames.