Keith Laumer is still in print from Baen Books, and judging from the covers of some of them, there's some posthumous collaboration going on. I wouldn't know, not having read any of them.
I became acquainted with Laumer's work long ago through books like A Trace of Memory and the Retief stories, which I still read sometimes when I need a laugh. For some reason, though, I'd never read any of the Bolo stories or any of those about the Imperium. So I thought I would.
As it turns out, I liked them all quite a bit. Worlds of the Imperium is about parallel time tracks, with Brion Bayard, a guy from our world, getting grabbed and taken to a different time track where the U.S. never existed. He's asked to replace the version of himself in yet another time track, one that's sending raiders into the second track. If that sounds confusing, I'm sorry. It's the best I can do. It's not confusing in the reading at all, and the story crackles right along.
The Bolo stories deal with sentient fighting machines. Really big machines. Huge. Often they're reactivated after centuries of disuse and have to be stopped by the people they once served. But not always. One of the stories in The Compleat Bolo was a Retief story I hadn't read, a nice bonus, even if Retief isn't facing down the Groaci this time.
I'm glad to know that Laumer's still in print. He wrote well, plotted well, and could make be funny when he wanted to. If you've never tried his work, give it a shot.