Here's a list of most of the shortcuts I've found over the course of 3 years (there's a lot so i may forget to include some):
Moving items inside inventories:
Right clicking while you're holding nothing= Gives you half of the items you clicked on. If it's an odd amount of items you get one half + one extra item.
Right clicking while holding something= Places one of the selected items to where you clicked on.
Right click and drag over blank areas while holding something= Placed a single selected item over the selected areas.
Left click while holding nothing= Selects all the items
Left click and drag over blank areas while holding something= Evenly spreads out the selected item over the selected areas. Left-overs remain selected.
Shift right click: Moves the 'clicked on' item to the next inventory.
(I don't know which shortcut this is :/) Moves all items of the same type into the next inventory.
/tp = teleports you or someone else to the specified location or player
/weather = Changes weather
/time set/add = Changes time
You can use the @a (all) @p (nearest) @r (random) and @e (entity) selectors instead of player names even in chat.
Using the ~ symbol instead of coordinates makes you or the command block use 'relative positions'. This means it uses whatever coordinate you're on plus the number you put after the symbol. E.g: I'm on X:35 Y:55 Z:90. I use /tp (my name) ~5 ~10 ~-5. This will teleport me to X 40 Y 65 Z 90
Shortcuts and useful things:
Pressing the CTRL (control) button while moving forward allows you to sprint instantly
Press F2 to take a screenshot
F3 toggles the world coordinate and basic world data display on and off.
Holding F3 and pressing B toggles the mob hit-box display on and off (what you need to hit in order to damage the mob)
Holding F3 and pressing H toggles the basic item data on and off. This shows item durability and item ID numbers.
F5 changes your perspective
Cinematic view: This key is disabled by default. You can assign it a key in the controls panel.