1. Reverse/dark colour scheme - or customisable colour scheme (and can base on sites colours).
2. Comparative sitemaps - show differences between this crawl and a previous one with differences highlighted - new and missing.
3. The thickness of lines between nodes based on % of traffic that passes through those two nodes - from analytics - thicker lines = more traffic would give you a very quick and visual understanding of site performance.
4. Ability to centre a node of your choice and have the other nodes arrange around the relationship to the node of choice.
5. Save the image as an SVG - bigger sites images are tine - SVG would allow you to zoom into the image to see the bits you want to (outside of Sitebulb - so good for clients).
6. There is no number 6.
7. Layers over the map that you can switch on to show where the hints are located - list of hints to switch on and off.