Update, I've now added Google's reCaptcha to the form, To submit the user must complete the reCaptcha, you will need to sign up to the recaptcha to get your site key and your secret key at Google.
This another contact form that is easy to use and is customised in CSS3 and Ajax, This form will popup on click of link/button and has a dropdown feature for enquiries ect, This is now ready for using, I've added basic enquiry info in to the form, You can change that to anything you wish, It's just an example of what can be done with it, I've also added most of the security features to the main javascript file so it'll remove the most malicious tags.
###Demo