From time to time, I (Cal Henderson) talk at conferences and such about web things.
Here's a list of talks i've given.
Future talks can be found on my homepage.noui=1
New users of Django, even people who have lots of experience writing database-driven applications, often run into a seemingly simple problem: how do you set up a model with “optional” fields that don’t always have to be filled in? Django’s validation system assumes by default that all fields are required, so obviously you have to tell it which fields it’s OK to leave blank.