I believe Gravity Forms is much more than a contact form, it can be used for pretty much any form you ever need, but I understand that $$ matters. Before I went with Gravity Forms I used cForms II. It has a lot of great options, but isn’t quite as easy to work with or extend.

I didn’t code any plugins into the theme, but I did code features in. For example, I coded in the rewteet button instead of using a plugin. I wrote a post about how I did that in my design blog. http://designsbynickthegeek.com/tutorials/add-hashtags-to-your-tweet-button