For example, if I were to plan a trip between Munich and Berlin by car, it'd be great to have a quick glance at a map that would give me a quick idea on where the interesting spots are. That way there's no need to stumble over dozens of pages on Wikitravel to see if there's something cool in the area that's easily reachable on a drive like this.
I've found a good example of an attractions heat map of London:
Is there something similar on a global scale?