Nice clear drawings give most of the details needed to build a wood framed house. Makes understanding how to build a stair or frame a dormer all that much easier.
http://www.awc.org/pdf/WCD1-300.pdf (http://www.awc.org/pdf/WCD1-300.pdf)
Load your printer with paper and print out this free reference book. (Thanks to Glenn K.)
If you want information on the beam and plank system that is used for loft floors in many of the cottage plans click this link:
http://www.awc.org/pdf/wcd4.pdf (http://www.awc.org/pdf/wcd4.pdf)
Update: 7/21/09 Downloads appear to be free again :D