Another favorite of mine. Makes navigation / moving files really easy. I mapped F10 to open nerdtree and F9 to open it with my current open file focused. The F9 mapping is really useful when I want to easily see "what else is in this directory?"
If you use git, this is a must have. My favorite time saving trick is using :Gstatus, you can then see all of your current changes and one by one review what you've changed. Either staging it, or removing it. Helps me review my code before commiting and catching any mistakes.
This one completely blew my mind the first time I saw it in action. If you use tmux, this is SO powerful. You can set it up to run commands from vim in another pane/window. I have it setup so with a couple taps I can run tests in another window. Allows me to see my code and tests run at the same time, with only a couple key strokes.
With speeddating it’s easy to increment time and date using Ctrl+a. If you’re having a date like "2017-01-31" and press Ctrl-a while having the cursor on the day, it jumps to "2017-02-01" :-)