Airfoils:
http://www.aviation-history.com/theory/lift.htm
http://www.av8n.com/how/htm/spins.html#sec-coanda-fallacy
http://user.uni-frankfurt.de/~weltner/Mis6/mis6.html
http://www.avweb.com/news/airman/185905-1.html
http://www.grc.nasa.gov/WWW/K-12//airplane/foil2.html

Icing
http://www.tc.gc.ca/tdc/summary/12800/12897e.htm

Shock and Vibration
http://www.fabreeka.com/tech/Primer_Vibr_Isol.pdf
http://www.fabreeka.com/tech/isolation_theory.pdf
http://www.anti-vibration-mounts.net/
http://www.vibrationmounts.com/Products.htm

GPS
http://www.maporama.com
http://jan.ucc.nau.edu/~cvm/latlongdist.html
http://www.mapquest.com/maps/latlong.adp
http://tiger.census.gov/cgi-bin/mapsurfer
http://terraserver.microsoft.com/
http://www.gpsworld.com/gpsworld/
http://rockyweb.cr.usgs.gov/public/outreach/gps/gps_websites.html
http://jan.ucc.nau.edu/~cvm/latlon_find_location.html

Sport Pilot
 

Experimental Light Sport Aircraft
 

Amateur Built
 

Airports and Flight Planning
http://www.fltplan.com  - Great flight planning site
http://www.flightaware.com - See what activity's going on at an airport