It's possible I've shared this elsewhere before, but every time someone reminds me of its existence I lose a good hour playing with it. It's an interactive online map of the Imperium, the interstellar government of Classic Traveller. I love this - it's so freakin' huge (that's what she said). The best part is being able to click on a sector, then a sub-sector, then a system itself and get images of the star and world. You can also click options for layers such as jump routes. Very cool stuff.