I had need for a reminder of a bit twiddling hack that I had forgotten, and found this useful page that included many I don't think I had seen before. These are mostly "too clever", and should be used sparingly in your code. You've been warned.
Need something to listen to on a really long trip? Librivox has just completed a huge audiobook version of the sixth edition of Charles Darwin's classic On the origin of species. It's a fascinating book, and well worth reading if you have any desire to understand the history of biological science.