Every Brainiac's domed city is equipped with its own gravity field generator
Superman handles Kandor very carelessly when he makes off with both cities. So carelessly he could have killed the Kandorians accidentally. They had to be protected by a force field. Brainiac is the origin of the Cybermen, the Borg, the Cylons, and whatever comparable concept you've got
Fragments of Brainiac have been seeded on countless worlds, found by countless species and inspiring them to develop computer technology. With more and more technological advancement, societies got increasingly dependent on Brainiac-based technology until it progressed to the point of artificial intelligence or cybernetics. Before too long, those countless societies are nothing more than a collection of cells in Brainiac's unimaginably vast Hive Mind.- And most recently Brainiac-tech has been used to create the source code for TV Tropes.
Brainiac will challenge Larfleeze for the Orange Lantern.
Not one of the drones Larfleeze took control of for some actual time, but the real deal. While largely emotionless, greed(specifically for knowledge) is the exception to the rule and Brainiac's defining trait. Willingness to destroy entire worlds for it puts even Agent Orange's greed to shame, and one could imagine him feeling he's a better fit for it than the current wielder. It could serve as the plot for a Superman/Green Lantern crossover.