It depends on your business model, but always the basics: Home, About, Services, Portfolio, and Contact. Beyond that, you may want to consider a blog (so flexible! just one article per month, when optimized well and created thoughtfully, can work to demonstrate your expertise and help your search engine optimization) and an FAQ page (another opportunity to feature the things that make you special). A testimonial page is optional. You're better off sprinkling the best ones all over your website...on pages that people tend to visit more often.