I’ve been wanting to start a collection of bokeh’s to use for different projects at work, replicating the characteristics of the circles-of-confusion for different lens and apertures. Once I get a decent collection together I’ll post them with tutorials. Meanwhile here’s a crazy looking one I’ve combined in Photoshop by shooting straight at an LED with my Canon EOS 350D, ISO 100, f5.6, 1/4000, Manual Mode, EFS 18-55 mm lens [ set at 55mm (x1.6) ] and a hand crafted one from Adam Paschke. It’s totaly impractical because of the colours, but hey it looks cool and that’s all that matters, right?

Here’s also some links which go right into camera and lens optics and talk about the bokeh.

Paul van Walree. My favourite because he gives a shit load of examples and pictures …
http://toothwalker.org

Wikipedia on bokeh.
http://en.wikipedia.org/wiki/Bokeh/

Ken Rockwell has some “interesting” ideas on bokeh.
http://www.kenrockwell.com/tech/bokeh.htm

Harold M. Merklinger is a bit of an export in optics. He writes some good info here and includes some nice side profiles of bokeh characteristics.
http://www.luminous-landscape.com/essays/bokeh.shtml

I’ve just come across this application which appears to do some really nice DOF post processing. It also has some really nice explanations and examples on DOF and Bokeh.
http://www.dofpro.com