So every time you download and install a game from Steam it downloads a DirectX redistributable package. Once your game is installed, that redistributable file just sits on your hard drive useless, taking up space. A hundred megabyte file may not be much, but if you're a heavy Steam user these files will add up over time.
Enter TikiOne Steam cleaner, a handy tool that will list every redistributable package stored on your Steam directory that you can then easily remove. Boom, freed up memory for more games. Or porn. In the case you need to reinstall a game or there's an update to one, Steam will detect you're missing the file and redownload as needed.
Some of you may already be well aware about this, good for you! But I had no clue until this reddit thread so I wanted to share in case there's a ton of you out there that were as clueless as I was.