Toying with introducing a new mechanic:
Burn the Books: Provided a technology has not gone public, you can completely destroy any records or knowledge of that technology within your home territories. This reduces the research cap for the tech by 10 for future research efforts and reduces the number of sides who have access to the tech by 1. You lose access to the technology completely, though any units built from it continue to exist until lost or disbanded. You will need to re-research the technology from scratch if you ever desire it again.
What with adwarf's rather impulsive desire to renounce magic, he might want to avoid it getting into the public domain as easily because of his knowledge of it. I make no judgement on his perceived market value of the tech he's researched.
There are plenty of undiscovered economics technologies, though I don't actually have them plotted out beyond vague inclinations. Things like Infrastructure are pretty well defined (improves investment cap in basic economy, number of industries), but there are also buildings like Marketplaces that will improve your economy based on how many resources you have access to (in the same way that Smithies do) and Banks that will give a percentage increase to your economy, but also cost upkeep (making them only worthwhile after a certain economic threshold).