Recently a possible feature came to mind which I don't believe Heidi has now but might be useful.
I keep a printed record of my databases so that I can reference them when programming and I thought it might be useful to export a table's definition, either as tab- or comma-separated values, or Excel. The export would simply show the view that you see in the table's BASIC tab: name, datatype, length, etc. Once in your printing program, you could easily delete any unwanted text.
Not a difficult addition, I would think, but quite handy.