In 2001 it telepathically educated primitive humans and made them more aggressive, leading them to become prosperous killers and hunters instead of starving prey. The one what's-his-face got sucked into ("it's full of stars!") transported him to a facsimile of a hotel room. When he fell asleep, he was transformed into a demi-god being ("star child") to serve the masters of the monoliths.
I forget what it did in 2010 and 2060, but in 3001, a monolith in orbit around Jupiter mass-produced itself and turned Jupiter into a second star. Another one on one of Jupiter's moons began telepathically educating moving seaweed monsters like the first one had humans millions of years ago, while producing a force field to keep humans from landing on the moon and interfering with the budding civilization there. I think they blew up yet another monolith by giving it a computer virus from what's-his-face when he rebelled against the monolith builders.
The civilization that built the monoliths was "dead" by the time humans became a true civilization. They had lost interest in wandering the galaxy seeding worlds with monoliths as experiments (make some species sentient faster than others, etc.) and over time they "evolved": their minds were transferred into giant interstellar starships/robots, then later turned into "pure thought" and they became god-like beings.