In Doctor Dobb's Journal, James Kalbach writes about the changing face of Web interface design. Historically, the rule of thumb was that a page should have 'seven, plus or minus two' items in a navigation menu. Kalbach suggests that, in the 21st century, we can do better than this. He provides several valuable points of advice, including this one:
Prioritize Navigation Types: Sites often have main, secondary, and tertiary navigations. The separation of menu types can be done by position on the page, font size and type, and color. You've probably already prioritized navigation types without knowing. Example: PayPal makes good use of various font weights and sizes to prioritize links, though lacking visual chutzpah. With spatially separated menus, the 40 links on the homepage present no problem. Compare: Fleet Homebanking has around 35 links, not counting the pull-down menus and search area. I found this page very difficult to use.