The text below is from sitemaps.org. What are the benefits to do that versus the crawler doing their job?
Sitemaps are an easy way for
webmasters to inform search engines
about pages on their sites that are
available for crawling. In its
simplest form, a Sitemap is an XML
file that lists URLs for a site along
with additional metadata about each
URL (when it was last updated, how
often it usually changes, and how
important it is, relative to other
URLs in the site) so that search
engines can more intelligently crawl
the site.
Edit 1: I am hoping to get enough benefits so I canjustify the development of that feature. At this moment our system does not provide sitemaps dynamically, so we have to create one with a crawler which is not a very good process.
Crawlers are “lazy” too, so if you give them a sitemap with all your site URLs in it, they are more likely to index more pages on your site.
They also give you the ability to prioritize your pages so the crawlers know how frequently they change, which ones are more important to keep updated, etc. so they don’t waste their time crawling pages that haven’t changed, missing ones that do, or indexing pages you don’t care much about (and missing pages that you do).
There are also lots of automated tools online that you can use to crawl your entire site and generate a sitemap. If your site isn’t too big (less than a few thousand urls) those will work great.