How important are design patterns in web development?
MVVM is a newer one I have seen used with Silverlight. It's a bit much, but it seems effective.
What are the design patterns that I should be completely familiar with? And what is one easy example that each can be used for?
I am a web developer (I use Django, and is familiar with separation of logic), but I work at a Desktop-app company.  They are always talking about singletons, and I forget...but it leaves me no clue!