A really good article for validation in PHP. For me form validation is always one of those headache things that I tell myself I will get around to, although the security of your site could depend on it. This article is good for people who worry about their users turning JavaScript off.

For people who wish to take the JavaScript approach, JC posted about QForms not too long ago and our friend Simon wrote a great article for Sitepoint titled, Simple Trick for more Usable Forms.