We have several good sites regarding lenses such as:
Bojidar Dimitrov's Pentax K-Mount page
http://www.bdimitrov.de/kmp/
and
Stan's Pentax Photography page
http://stans-photography.info/
Bojidar's site contains a lot of objective facts and is a key reference site for me, whereas Stan's site contains subjective user opinions telling us how the lenses perform in practice.
Unfortunately, Stan's page is not being updated, and I therefore propose that we use this forum as a continuation of Stan's site.
Let's start one thread per lens, and post our experience and some photos taken with that lens.
Anybody should feel free to start a thread about a lens you own, use, hate or love, and to add posts to other folk's threads.
For my part I'll start out with the 17-28mm fisheye zoom.