I thought I would add some pointers for aircraft scratchbuilding.
There are two nice aircraft scratchbuilding books edited by John Alcorn, titled "Scratchbuilt!" and "The Master Scratchbuilders!". I've had to read through them carefully to get the most out of them, since they're a bit disorganized (the text describing something is often several pages away from the relevant pictures and they often just have text descriptions of techniques).
These two links contain useful information about scratchbuilding aircraft:
http://wwimodeler.com/harry/woodman.html
http://www.wwimodeler.com/esc/wings.html
I also find useful technique information and plans in the RC flying community. This site is probably one of the best of the bunch for techniques:
http://www.airfieldmodels.com/
Here's a sample list of websites with plans available (either for download or purchase by mail). The best plans include 3-views plus fuselage cross sections. Sometimes you don't get much more than a single line drawing, depending on the obscurity of your subject (I have a few planes I want to build that I can't find any plans for yet). Quality is usually hit-or-miss.
http://www.bobsairdoc.com (Huge mail-order selection)
http://www.vought.com/heritage/html/down.html (Fantastic resource)
http://www.seawings.co.uk/ (Flying boats - look under "References")
http://oldbeacon.com/plans/resource1/resource_page-1.htm (Between-the-wars)
http://mkmagazin.almanacwhf.ru/avia/ (in Russian, but good stuff if you poke around)
http://richard.ferriere.free.fr/3vues/3vues.html
http://hawker.smugmug.com/Hobbies/15578
There's more out there, but this should give you an idea of what's available. Other sources for plans are books like the "Detail and Scale" series, and a long list of magazines.
And for inspiration, my current project (the An-124 and An-225 in 1/72 scale):
/forums/754234/ShowPost.aspx
A nice thread by Solid on scratchbuilding from a while back:
/forums/673793/ShowPost.aspx
If there's a subject you really want to model, and no kit exists just take a stab at it. The An-124/-225 is my first complete scratchbuild, and it's been a steep learning curve. I take two steps forward and one step back sometimes, but I'm learning a lot and having a lot of fun.
Enjoy,
Bruce