I gave these to the high school kids that I mentor Robotics for - they each seemed to find different puzzles that they liked, so I consider that a win. These are the same kids who had fun learning binary search as a way to always win "high-low" guessing games, so they were already interested in logic.

My personal favorite from Tatham's puzzles is Net - I have it on my phone, with 15x15 wrapping being a nice way to relax and spend some time.