Our newest WordPress plugin is the Secure and Accessible PHP Contact Form, found at BeastBlog.

I prefer it to WP-Contact or cforms, for aesthetic reasons mainly, but this one has a lot of features! From the plugin site:

• Form overview page available to you to confirm the plugin’s general configuration.
• Extensive security features with 16 individual abuse countermeasures.
• Build to the highest web standards with maximum accessibility and usability in mind.
• Extremely simple drag-‘n’-drop, plug-‘n’-play set-up — even novices can do it.
• Simple 7-step form-based configuration so you never have to look at one line of code.
• Form set-up error management to help ensure you set-up critical parts correctly.
• Style choices at the ready with some pre-made form themes designed for several popular WordPress themes… all pre-tested.
• Ability to use “no themes” offered in case you want to use your own style sheet.
• Built in Style Sheet Editor so you can edit the available themes or create one of your own. A commented “custom.css” file included for you already.
• Extensive on-board documentation library so help is always at the ready.
• Performance monitoring spam counter function.

I still have to tweak the formatting a bit to match the site, but there are quite a few ready-made themes that may fit your site as is.