Off the top of my head:
And then Callahan's Lady and The Lady Slings The Blues (Booze?), which are about a different main cast of characters. I'm sure I missed a few, but there's a list here.
His collaborations with his wife are pretty good, too. He's probably my favorite sci-fi author, or at least in a 3-way tie with Heinlein and Asimov.
"I never let my schooling get in the way of my education." -- Mark Twain