After Mark Jaquith tweeted "Uninstall "WP Contact Form 7" -- it is being exploited" - it's surprising to me that the plugin still shows up at the top of the list of wordpress.org plugins. Cforms - the best plugin for the job - has still not been re-listed on wordpress.org, despite being GPL'ed some months ago. As I said on my work blog,
This is far and away the best contact form plugin there is. The reason? configurability. You can easy build literally anything with it. We’ve built out employment application forms, wedding checklists, and more for clients. It also drives our own quote form. There’s also built in spam protection, via question and answer or captcha.
If you need a contact form , or any kind of form (share this via email, file upload, schedule request, etc), go use Cforms.