If you are not making site maps I would highly recommend it.
I am currently using http://www.freesitemapgenerator.com , as the name indicates they have a free service and a paid service. It crawls your webiste and generates a sitemap. A really great free service!
My biggest complaint would be the speed of the service, I guess a lot of webamsters are taking advantage of the free service so it can take a few days to get your sitemap if they are busy. This can however be avoided by using there paid service... which I find expensive.
