Ice and anti-inflamatories for the knee. Take it easy when you start riding again- flat short rides. Try not to get too frustrated, it'll come around.

I hear you on the helmet. After my last crash (high speed face plant) I looked for the helmet that had the most coverage on the front and sides, and wound up with a fancy Specialized helmet. It's worth a $50 extra and a few more grams to have a bit better protection.