I've seen a few, and tried out Contact Form 7, which is pretty good but by default looks quite ugly.
I've also had a quick dig, and it looks hard to add some hooks for CSS. It also doesn't use the label element.
What is the best standards compliant easy skinnable contact Wordpress plugin in your experience?
I just found out how I can add my own label elements and get it to work with Contact Form 7.
cform is highly configurable and handle the customization of the css very well, right from the control panel or via ftp, whichever you like best.
UPDATE
We also use "Fast And Secure Contact Form" on our Wordpress MU network, and it works a treat.
You can give these two alternatives a go or even create your own by posting to the page itself and using some custom code in your functions.php file.
I've used cformsII quite a bit and it comes with a library of skins, a click-to-build interface, and pre-built forms. It's got loads of options and is incredibly robust for a free plugin. Some other great features it has an auto responder and you can even have it post form data else where for further customization.
There's a new plugin called Formidable I use and like better than others I've tried. Its drag-and-drop interface makes it so easy to use that I can let clients set up their own forms. The free version is sufficient for most needs, and if you're willing to upgrade to the paid version ($35 for a single install, $97 for infinite) you get reporting and a number of additional fields.
i really like "contact forum 7" look for it in the wordpress extend also i agree with hsatterwhite, the Gravity Forms is great but its not sample as contact forum 7