It really is good to have checklists...
Tuning Up Your Web Sitehttp://www.seochat.com/c/a/Search-Engine-O...-Your-Web-Site/QUOTE
So how do you know if your site really needs an overhaul? Start by checking your search engine referral and site traffic figures. You want to get several months' worth of figures. Chart your progress. Are these figures growing? And just as importantly, are site visitors doing what you want them to do (i.e. converting, buying products, ordering newsletters)? If not, it's time to get your site up on jacks, break out the tool kit, open the hood, and get to work.
This article seemed to be a good outline for measuring the "pulse" of your website's progress.