I'm looking at the three options for Hostgator. With the Business option you get a Free Dedicated IP. What type of sites or set up would actually need this?
My personal rule of thumb is that if the site is of important, or makes a significant amount of money - it's worth having it's own IP. If it still holds true, some search engines analyze the IP a website is on in determining the "strength" of links. If all of your sites are on the same IP, and all link to eachother, not as much weight is passed or value given to the link because it could be an attempt to manipulate rankings by a site owner. A dedicated IP is *never* a bad thing, but if you're just starting out in the internet world, there is no reason to necessitate over-head above and beyond what is necessary because the benefit is negotiable. (In my opinion).
Good one Dedi IP are usually used for SEO factors although not that relevant but its always a good idea to have your own dedi IP for your business as you won't want to associate your site with eg:fishing sites etc
You can only use SSL (non-shared) for your website on a dedi IP, that is most of the time the readson why websites do have a dedi IP