Check out the four sample master pages released by Microsoft, they include;
Master pages are a feature of ASP.NET 2.0 that work the same way in Windows SharePoint Services 3.0 and Microsoft Office SharePoint Server 2007 as they do in ASP.NET 2.0. Using master pages, you can create a single page template and then use that template as the basis for multiple pages in an application, instead of having to build each new page from scratch.
Microsoft has made available a package of sample master pages compatible with the Application Templates for Windows SharePoint Services 3.0 to showcase some of the customization options master pages provide. The master pages were built using new CSS and Master Page editing tools within Microsoft Office SharePoint Designer 2007.