Biologist link (I've not done one of these in a long time):

Lungs in Health and Disease (An NIH publication; opens as a PDF file). A very good basic introduction, in "intelligent layperson" writing, on how lungs work and some of the diseases that can affect them.

I'm sitting here, now that I've done that last bit of tinkering with my gen. bio. lecture on the respiratory system, reading knitblogs (but keeping a page about asthma open so I can jump to it if someone "important" comes by).