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This (ugly) form is an example of a few of the features of Data.FormValidator.js.
Please note, FAR more customized validation is possible with this module.

password (required)
tinymce textarea(required, must contain "george") (NOTE: this will only test the tinymce support if the TinyMCE library is loaded.)
textarea(optional, but required if "text1" is filled in)
text 1 (requird, must contain the text "bob")
text 1 (requird, must contain the text "bob")
text 2 (optional, but must contain both "sam" and "mmy" if it is filled in)
select-one (required, must contain "test")
select-multiple (required, must contain "test")
select-one (required, must contain "test")
checkbox: asdf qwer(required)
radio: 1 2(required)
dependency group: (if any of these are filled in, they all must be filled in)
file: (required)

Build In Constraint Tests email (must contain valid email)
state (must contain valid state)
province (must contain valid province)
state_or_province (must contain valid state_or_province)
zip (must contain valid zip)
postcode (must contain valid postcode)
zip_or_postcode (must contain valid zip_or_postcode)
phone (must contain valid phone)
american_phone (must contain valid american_phone)
cc_number (must contain valid cc_number)
cc_exp (must contain valid cc_exp)
cc_type (must contain valid cc_type)
ip_address (must contain valid ip_address)