It would be cool if the buildings in the building menu:

• are color coded (make the unique buildings purple text, etc..)
• would have a function to shift-click on a building, then have it greyed out in the future if you access the specific solar system again. It would give me a much clearer picture of what I did and did not want to build on a planet. It would also automatically 'highlight' the new available buildings & the buildings I didn't grey out.