Here's another great example of a quality french drain using schedule 40 perforated PVC and tons and tons of gravel.
A good french drain should include:
Angular gravel, washed
Solid Perforated sch 40 PVC
Proper slope ~ 1/8 bubble heading downhill
~ 24" of gravel surrounding the pipe
No sock or geofabric to clog and restrict flow
A clean-out with vent holes
A logical place to send the collected water
Thanks to bob (the slacker) for his tips on making this the best french drain I know how to install.