-Alfred:
So much better than spotlight. Download it from the dev site free or the Mac app store.
-Popclip: pretty cheap now in MAS. You can quickly cut, copy and paste items and there are also extensions available to make tasks quicker and easier. This along with Alfred should be included in ALL Macs.
-Little Snitch: block any unneeded/unnecessary connections. If you somewhat value your privacy, check it out but its not for everyone. Trial and license available on the devs
website.
-Temperature Gauge: I use it mostly for tracking fan speed.
-Jumpcut- keeps track of your "copied" text.
Other apps I use but not quite as much
-Moom: place your active windows in certain areas.
-Boom! in some cases my MBP volume isn't loud enough but boom can raise the volume even further.
-Gemini: duplicate finder.
-Screenflow- record your screen. Well worth the asking price.