Hey..
I do this stuff for a living and have a few years..
I write some tutorials and do work currently with a group called Broadband Mechanics http://broadbandmechanics.com

"Well designed" is always subjective.

I consider one tutorial I did on phpgtk (http://lucifer.intercosmos.net/tut/) to be well designed, but another might find it cumbersome.

For me, one system I looked at, that I can think of, that struck me as nice was an ad server called OASIS which led to the following SYSV-SHMOP based content caching engine.
http://lucifer.intercosmos.net/?view=SNIP&item=120

Oftentimes I would say that places like hotscripts.com and others are not necessarily the best place to be looking for "example" code.. Great to see someone's 'first' code post or to see what people are working in the general..

Cheers
-joeldg