We use MindManager extensively for all sorts of things, including as an interesting way to lay out a web page. Mind Maps make great 'front pages'
As for integration with a database, I think it depends on what you mean by that. MindManager can export to XML amongst other things meaning that it should be pretty straight forward to have some kind of mind map 2 database translation.
Given that Mind Manager can also integrate with other Office applications (and that it has an extension architecture) I suppose it may not be that difficult to integrate with ODBC for example... Great software, shame its windoze only.
Howevever in terms of 'dynamic' maps this way be more tricky. Some kind of interactive mind map interface would be great, but I seem to recall that freemind etc are fairly basic applications.
Anyway, in essence I see no reason why documentation stored in the database couldn't be translated into mind maps.