ourHost.com has been involved in SEO (Search Engine Optimization) for going on 10 years+. Ecommerce managed hosting is our core competency. YourHost.com is very cautious on what we recommend for tools for our customers. We try and test, then recommend, if they meet our strict standards.
Up until this article, we have performed of our site submissions manually, along with using some limited select tools we have come to trust, but far from not perfect. Our developers are very cautious and we want to make sure our customers's are sites are accurately submitted.
Google and our Shopping Cart, ShopSite, offer a sitemap generator tool, they are ok but not perfect. Currently they do not submit in XMS so they have to be interpreted by the leader, Google.
If you use an ecommerce tool like ShopSite, it will allow you to generate a site map to submit to google.
There are many sitemap tools you can use but you should always manually review what it found so you do not submit bad links or missing pages, which will lower your overall Page and SEO ranking.