I'm assuming you're talking about an XML sitemap? To generate XML sitemaps you can use: http://www.xml-sitemaps.com. If you're using WordPress, you can use a plugin to generate your XML sitemap: http://wordpress.org/extend/plugins/google-sitemap-generator/
Well I don't have any personal experience with any so I wouldn't feel comfortable recommending one. I would do a Google search for "HTML sitemap generator" and see what you find.
Google Webmaster Tools is just for XML sitemaps though, not for visual HTML sitemaps that your visitors can navigate and use.
Go to Google and type XML sitemap generator. Type the URL of your site and press the create button at the bottom. Your XML sitemap compatible with Google will be created. Now all you need to do is put this file which you have downloaded at the root directory of your website.