Spam Prevention/Reduction - Contact Form?

I want to add a simple Contact form to my web site so that customers can contact me easily.

<form>
    NAME
    <input type='text' name='name' />
    EMAIL
    <input type='text' name='email' />
    MESSAGE
    <textarea name='message' />
    <input type='submit' />
</form>

This form would simply email me the customers message.

But, I also want to reduce (not, I'm not saying eliminate but at least reduce), SPAM.

I've looked into using CAPTCHAs but, ultimately, I don't want to hinder the customer with having to fill out extra information.

Any ideas of a good simple spam prevention/reduction method I could use for my Contact form.