Do you use Adobe Premier Pro CS5, CS6, or CC on an iMac or Macbook Pro? Have you noticed video rendering takes a really long time? This may be an easy way to fix it, by enabling CUDA hardware acceleration support.
A lot of people find the ASCII based command-line text editors (like Vim) a pain to work with. Here's a few suggestions on how to easily invoke TextEditor (or any other GUI based editor you prefer) from the command line in Terminal.
People who relied on color labels highlighting files and folders in Finder on per-Mavericks OS X were dismayed to discover this feature was removed by Apple, with no option for recourse. Here's an easy and free way to restore color labels (aka. tags) on filenames and folders in OS X 10.9+