There aren't many plug-ins which defy explanation but Inflator is one which comes close. Designed to increase apparent loudness, Inflator achieves this without use of compression or limiting - an apparently contradictory statement. The simple interface doesn't hint towards the power of this plug-in to achieve the apparently impossible: To make signals louder without turning them up! The fact that this is also as close as you're likely to get to a "Betterizer" means that for the letter I there was only ever one contender.
I've always wondered exactly how this plug-in works. The manual hints towards some mathematical voodoo - Apparently relative probabilities of higher sample levels resulting in an increase in average modulation densities.
When I asked Sonnox how it works they confirmed what I had suspected all along. It actually is magic!