BetterTouchTool - Just discovered this little gem and it’s great to be able to do more with touchpad gestures. Window snapping feature allowed me to get rid of ShiftIt.
Dropbox - If you haven’t heard of it or don’t use it, welcome to Earth.
Meteorologist - Handy weather, click for details, extended forecast at radar.
ClipMenu - Clipboard organizer and also useful for doing “plain text” pasting in apps without that option natively. Can configure the number of items it remembers.
Caffeine - Because it is handy at times.
Display - Because I use an external display fairly regularly, but not always the same one.
Battery - I know there are slicker third-party ones out there, but the native one does what I need.
Bluetooth - For moving stuff to/from my dumbphone.
Wi-Fi - Sometimes you need to check or tweak stuff. I use multiple networks in the course of most days.
Date and time - Because I always forget and 12-hour time stinks.
Spotlight - I occasionally use it to search, more often as a simple calculator. (Just type in your equation!)
(From Chris Moellering)