how many meta keywords should I site have?

[virgohippy]

How many keywords is really a vague question.

What's far more important than meta is what text you have on the page. Optimizing with keyword meta really isn't going to do much unless you can write 200+ words of unique text.

Keywords should be based on what you have in your text. With sparse text, a few keywords is really all you have on a page anyway.