Here are two sites, although they are rather lengthy in discussion, and focus more on bigger boats....

http://sailing.about.com/gi/dynamic/offsite.htm?site=http://dixdesign.com/lofting1.htm

http://sailing.about.com/gi/dynamic/offsite.htm?site=http://persweb.direct.ca/tbolt/lofting.htm

Lofting a stripper is easy. Why? Because you are actually lofting flat cross-sections of the kayak, which will be the forms. Each offset is a point on a drawing. When the points are all connected with a faring batten (straight piece of flexible wood or plastic) you will have 1/2 a form. Since the forms are symmetrical you can actually fold it over, trace it, and viola... a whole form. You don't really have to think in three dimensions.

Lofting a stitch-n-glue, on the other hand, is more complicated, because you are lofting long sections of the hull that are layed flat. I won't even try to get into that. Like the others said, Nick's book does a great job. There is a book on lofting available from www.woodenboat.com, but when trying to copy the link location I couldn't. Go to www.woodenboat.com and search for "lofting." That's the title of the book.

Good luck!
-Malcolm