I toss my racquet into my off hand after points. It doesn't flip or anything. I just kind of throw it in stride as I am walking back to the line from one hand to the other. I catch it at the throat and that hand stays there until I return serve again, of if I am serving until I get back to the line, pick up balls, or what have you...
I never knew I did this until a few weeks ago, so I can't tell you why I started.
I kind of wish I had some more interesting ones, I will have to see if I can develop some.
winter makes it hard to practice serving. off again on again til spring....sigh