Windows 8 doesn't have a Start button. If you don't think that's something that needs fixing, you're probably in the minority, at least for now.
Maybe in time, Windows 8's Modern-style Start Screen will grow on users and it'll turn out Microsoft was right all along. Until that happens, there's a flourishing niche of aftermarket utilities that bring the Start button (and menu) back to Windows 8, from excellent ones like Stardock's Start8, to ones that add value like Pokki. But you don't need to pay to get a Start button: There's one tool that's free, open-source, and very customizable. Meet Classic Shell.
Unlike most Start menu replacements, Classic Shell has been around for a while. Its first version came out in November 2009, long before Windows 8 was even close to public. At the time, it was meant to fix interface annoyances in Windows Vista. That was version 0.9 (the first publicly available version), and today, more than three years later, it's at version 3.6.4. As software projects are wont to do, Classic Shell grew over time, and now consists of three separate parts: Classic Explorer, Classic Start Menu, and Classic IE9.
That tendency of software projects to grow and morph over time is exactly what Classic Shell sets out to fix. It doesn't try to invent anything new: In the project's own words, Classic Shell is "a collection of features that were available in older versions of Windows but were later removed." You're not going to find any groundbreaking UI innovations here, but that's a good thing. These are interface patterns that worked and that Microsoft took away for reasons unknown.
Classic Shell's most newsworthy component is Classic Start Menu. Hit the Windows key on your keyboard, and up pops a Start menu, just like you remember it from Windows 7 (or Windows Vista, or Windows XP–you can choose your own skin). Start typing to search for programs, hit Enter to launch. Search is fast. You can pin items to the Start menu, and customize every aspect of it. Never use the Printers item? No problem, you can easily make it go away. In other words, Classic Start Menu is just like the Start Menu you know and love, only more customizable.
Classic Explorer fixes Windows Explorer annoyances by adding a toolbar with common operations (copy/paste, go to parent folder, etc.), showing the free disk space and the total size of the selected files in the status bar, disabling breadcrumbs on the address bar, and more. Much like Classic Start Menu, it is very customizable, so you don't have to use all of its features.
Before you spend any money on a Start Menu replacement for Windows 8, you absolutely must check out Classic Shell. Its lean and customizable menu gets the job done with no fuss, and gives you the exact Start Menu you've always wanted, no matter which version of Windows it comes from.
Note: The Download button on the Product Information page will download the software to your system. This file is donationware; the developer offers it for free, but encourages donations toward its development.