[R] mixed models

[Rob Knell]

Hi folks

Can anyone direct me to a guide to analysing mixed models in R that is 
understandable by mere mortals (or worse, mere biologists)? I have read 
MASS and also Mick Crawley's book on the subject, have thrashed my way 
through the various help files from the NLME package and I'm afraid I 
remain baffled :-(. Particularly confusing is exactly what groupedData 
does, how I should use it to define the structure of my dataset and how 
I then use that to define a model in LME. So pretty much everything 
then.

Thanks for any help

Rob Knell