Just saw a cool demo of XForms and Orbeon Forms.
Web Form Validation With jQuery
Josh Bush’s Masked Input Plugin and Paulo P. Marinas’ AlphaNumeric are both jQuery plugins to prevent input of invalid data in web forms.
Interesting WordPress Plugins
WP Contact Manager turns WordPress into a contact manager. It’s a combination of theme and plugins (including Custom Write Panel) that allows you to enter and manage contacts as blog posts (familiar, eh?). Use Members Only to secure access.
TDO Mini Forms “allows you to add highly customisable forms to your website that allows non-registered users and/or subscribers (also configurable) to submit posts. The posts are kept in ”draft“ until an admin can publish them (also configurable).”