title: LINQ practice exercises or puzzles?
body: <p>I'm still trying to learn LINQ, though it's going more smoothly now that I've started to use it daily at work. I still don't feel <em>good</em> at it, though. Does anyone have any challenging practice exercises or puzzles I can use as a code-kata to improve my skills?</p>
  
  <p>I'll leave this as community wiki, so maybe it can grow to a community list. </p>