I'm trying to figure out the best way to document and plan my database - looking both for good ways to show the ER diagram, as well as ample ability to comment on different pieces of it. Up until now I have used the relationship diagram in Filemaker itself to do this, but it has limitations in how well you can show certain things, and in how much you can easily comment.

I was considering using MySQL workbench - at least to document the key relationships. It seems to have more flexibility around the diagram, and ability to create locked layers. I may not enter every single field in there since that will be a lot of duplicative work, but I'm thinking it might be a good way to more clearly see the important relationships. (I'm about to do a major redesign of a new database, so this seemed like a good time to try to be more systematic about this).

What do others do?

I usually use OmniGraffle on the Mac for mapping out relationships. There might be other tools. Let's see what others might recommend. There might be some good online mapping tools, too.

MS Visio is my tool of choice

Thanks Agnes! I should have specified I work on Windows. But it looks like OmniGraffle is a general purpose diagramming program, perhaps something like MindMapper. You don't miss having something specifically designed for databases? (For instance, that might understand primary and foreign keys).