Crawl Database is the Search database in MOSS 2007.
Configuration Database
The configuration database handles all administration of the deployment as well as re-direction of requests to the appropriate database. It also manages the load-balancing for the back-end databases. When a WFE server receives a request for a page in a particular site, it checks the configuration database and identifies which content database grips the site's data. The configuration database concepts are the same as we have seen in MOSS 2007. In Microsoft SharePoint Server 2010 the Sitemap is serialized to disk to improve performance and reduce database callback operations.
Content Database
The back-end content database stores all site content, including site documents or files in document libraries, list data, and Web Part properties, as well as user names and rights. All the data for a specific site resides in one content database on only one computer. We can configure RBS as an alternative to this. I already have an article about configuring RBS in SharePoint 2010. Please refer to that for more details about it.
User Profile Service