Bikesport Michigan has some excellent photos comparing good positions with bad:

http://www.bikesportmichigan.com/bikes/karma.shtml

All of these pictures and fit comments are regarding riders on tri bikes (with aerobars), but they illustrate positioning issues that apply quite clearly to road bikes as well. If you are showing them to others just keep in mind that tri bike geometry tends to encourage a more forward position on the bike, so the rider's position vis-a-vis the bottom bracket may look a little different than an ideal road position for that rider.