How much should I charge for making a web site?

I'd suggesting writing each 'job' down.

i.e.
Design Layout in Photoshop - 3 hours.
Convert layout to xhtml/css - 3 hours. etc

Create module 1 - 2 hours

Tally it up.

Then think to yourself what kind of site it is, will they make lots of money or is it for basic information. Give a possible percent markup for sites that will make more money. i.e. Charge 25% more if they're making profit.

Ask yourself how much you're worth and how many items you can show them that you've done.

So an idea is: If they're going to make money off the site and you want to charge lets say $25 an hour for 30 hours. I would do:
25 * 30 * 1.25 (1.25 = 25% markup)

Things I would not do: I would not/will not work for an underpaying custmer. They tend to want you to do top notch work for little to nothin, as if you're running a sweatshop. If they're local I would come up with some sort of contract/agreement.