I love contextual menus. In Mac OS X, you find them when you right-click, two-finger-click (on a trackpad) or when you hold down the Control key and click. They're handy in scores of applications and in the Finder; if you're looking to supercharge your iTunes usage in particular, Macworld's Kirk McElhearn has published 10 ways to use contextual menus with iTunes.
One particularly useful option is to "Start Genius" from any track. When selected, iTunes will instantly create a genius playlist from that track. The "Add to playlist" option is also useful. When selected, you get a hierarchical menu all available playlists (smart playlists are excluded). Simply click the one you're after and the track is added.
Contextual menus also work on multiple tracks at once. Make your selections by either Command- or Shift-clicking, then right-click one of the highlighted songs to see the contextual menu. From there you can add that group to a playlist, adjust ratings, convert tracks to Apple Lossless format, and so on.
There's an important iTunes contextual menu that didn't make Macworld's list. If you connect your iPhone, iPod touch or iPad to your computer, you can right-click the device's icon in the iTunes sidebar to see a specific contextual menu for that iOS gadget. You can quickly eject, restore or back up your device; also, if you're about to update your version of iOS but iTunes is warning you that you need to transfer purchased items from your device back to iTunes pre-update... well, here's where you do it, via the Transfer Purchases command.
For all ten Macworld tips, read Kirk's article. In the meantime, please share any favorites with us below.