Getting the Week of the Year

I'm trying to make a PHP-based site that archives by week, like Fark does. Thing is, I don't know how to query by week of the year.

How do I do that?

It's >>3 again....

If I use WEEKDAY() with the date a row is inserted, I can just use the date of `date - WEEKDAY(date)' for the Monday I need.

Am I even REMOTELY correct?