Glenn Pennycook has written an excellent article titled All about avalanches  over at Mountainz . It looks like a good summary of the theory behind avalanches, and leads into what looks like some good guidelines about how to assess avalanche conditions. Definitely worth a read. (Thanks shanec over at the wtmc forum  for the link.)
I haven’t done a lot around snow (yet), but I’m looking forward to a snowcraft course up at Ruapehu over the next few weeks.