programming conventions

I'm trying to make my R scripts more readable by others, so I searched for
some R programming conventions and found the following two:

- http://www.ci.tuwien.ac.at/Conferences/useR-2004/Keynotes/Maechler.pdf
- http://www.maths.lth.se/help/R/RCC

the latter being quite extensive. Are there some other sources that might
be useful?

Thanks in advance,

Sebastian P. Luque