Businesses also use it for all kinds of websites from Ecommerce to News Magazines. The sky is the limit. If you know what you are doing, you can do whatever you want with it: http://en.wordpress.com/notable-users/
You can create a sites/blogs/shopping sites/gallery sites..... And you will customized the wordpress pugins as per your needed...
WordPress can be used for anything, I've used it to create eCommerce sites, I've used it to create portfolio's and I've used it to create website hosting sites that integrate with WHMCS. It really is a powerful system