What do you mean by 'like Constantine and Matrix'? These are the films he's currently set to do (though some aren't yet confirmed):
1. The Private Lives of Pippa Lee (being released now) - he's in the supporting cast playing the protagonist's younger lover
2. Cartagena - about an undercover operative who infiltrates the Colombian drug cartels
3. Passengers - about a guy who wakes up 100 years too early from suspended animation, and has to face the dilemma of living the rest of his life alone on a spaceship; the story was partly Keanu's idea, and he hired writer Jon Spaihts to do the actual writing
4. Chef - about a Michelin chef chasing his third star after deciding to give up his life of ruin; has been described as a 'celibate sex comedy'. Keanu was also responsible for the story, and Stephen Knight wrote the script.
5. Jekyll - a modern-day take on The Strange Case of Jekyll and Hyde, with Keanu playing both titular characters
6. Cowboy Bebop - the film adaptation of the anime
7. 47 Ronin - based on the true 18th century Japanese story about a band of samurai who avenged the death of their master
8. Henry's Crime - another of Keanu's writing efforts, this time with Sacha Garvasi, described as a 'dark romantic comedy'
9. Shadow 19, written by Jon Spaihts, about a space marine who is hired to terraform an alien planet for human civilisation, only to discover that he's not being told the whole story. This was the script that impressed Keanu enough for him to hire Spaihts to write Passengers.
Hope this helped. :)