You can get to the AppExchange listing here: https://sites.secure.force.com/appexchange/listingDetail?listingId=a0N30000003KNErEAO .
Since I love entity relationship diagrams, I had to check it out. I find a good ERD can help keep you sane when dealing with large data models. And I'm frequently annoyed that I can't find ERD Tools that meet my needs. I feel like I've tried every ERD Plugin in eclipse and been disappointed everytime.
This application is very simple. Once you install it, all you have to do is select which objects you want to have available on the ER Diagram. It gives you a simple multiselect picklist where you pick and choose the objects:
After you click Save, it will take you to the Diagram page. Here you click the Sidebar button in the upper left to select which Objects you want to display in your ERD.
Now all you have to do is click on those objects, and the applicaiton will automatically start plopping the objects on the ERD. By default, it seems to give you the small (non-expanded) entity, but if you click the plus sign in the upper right it expands it with the field level information. Very cool! You can drag and move the entities around straight in your browser via HTML5 Canvas tag.
Bottom line: If your a SF Consultant or Developer who needs to generate ER Diagrams, check this tool out. I'm excited to see what other enhancements they add to this tool. Some cool enhancements would be the ability to save your diagrams to a file, and or email diagrams from straight from the tool to clients.