Q:

Are there any good tools to generate a Google Sitemap?

Can you recommend any tools? Should we build our own? Should we create the sitemap manually?

A:

The Google Sitemap Generator for IIS generates a sitemaps based on actual HTTP requests to your server (unlike other sitemap generators that rely on a crawlable path from the homepage, Google's approach doesn't actually crawl your site).
It is uniquely suited to dynamic applications, particularly those that have a deep bank of data that's surfaced through user queries alone. 

