You use WordPress? They have a sitemap plugin. If you have a small site, there are free ones that generate sitemaps for websites under 500 pages, just google it. Your site bigger than 500 pages? Use this Java tool http://www.auditmypc.com/free-sitemap-generator.asp Code (markup): It worked for me, but takes some time to understand.
Google Code has a sitemap generator available, though I have never used it. It's one of the top results for "Google Sitemap Generator."
I have a website that helps sell online. It's basically a classifieds website... So i would need a software that could generate a sitemap for too many pages...
There are so many tools available online and you can Google it. But, a good one should can include or do these: 1. No page volume limited. 2. Can generate XML,GZ, TXT or HTML Sitemaps and submit & ping them to all of major search engines. 3. Make a schedule to automatically do all of works and save your time 4. Check broken or dead links. 5. Easy to use. Hope you can find a useful one.