I apologize if this has already been suggested, but to add more incentive to explore the universe, it would be great to have randomly generated (i.e. not something you can google) artifacts that can be brought back to Kerbal and placed in a new museum building at the space center. Some more common than others, like "Mun Rock" and more rare like "Strange Jool Alien Artifact." Smaller ones can easily brought back on kerbals, while larger ones would add mass to your lander. Something nice to show your buddies and brag about. Just a thought!
