Atlantis Data Surf is a free animated graphing tool which allows you to easily visualise complex schemas - use it to "surf" through your data.
At the heart of Data Surf is the "Surf Graph", automatically picking the most optimal layout, it allows one-click navigation through your data by means of graphical nodes which are connected by your schema's foreign key references.
Data Surf allows even the most complex of schemas to be easily browsed by representing the data's normalised structure in a way which people can easily understand.
The Surf graph and be zoomed, panned, coloured, rearranged and exported to produce a print-ready cheat sheet to accelerate your development and understanding.
Data Surf is a completely free product, so there is only the Community edition available, with full functionality.