There are so many application servers that it's difficult to suggest a particular one. Some application servers cater to specific website categories like blogs, wikis, or eCommerce; others, called CMSs (content management systems), are more generic. If you're building a dynamic website, take the time to choose technology that fits your needs. Unless you want to learn web server programming (which is an exciting area in itself!), you don't need to create your own application server. That's just reinventing the wheel.