I took over this site several years ago. It was originally designed by another company, however, the site was taking a long time to load, and did not provide for an easy way for customers to contact the company.
I initially redesigned the layout of the website, shaving off almost a megabyte of download per page by optimizing the navigation structure. This was done using CSS Sprites, and removing table based layouts. This produced a faster downloading site, that appeared quicker to the end user, reduced the bandwidth requirements of the website, and improved the SEO by using more text on the website.
Over the next few months we started adding features such as a jQuery counter to show how many feet of artificial turf was being installed, and a feedback form for users to fill out to send info about their project to the company. This form has some basic anti-spam tools built into it, without requiring the use of a CAPTCHA, which turns customers off.
Additionally, where the original designer had no information hierarchy on the website, I have gone in and added header tags and other markup language, instead of just using a CSS class or two, so that search engines can more easily identify themes for the website.