Here's the list of the most useful:
Shift + left-click on an ingredient will toss it directly into the cauldron.
Control + left click on an ingredient to toss it into the mortar and pestle.
Shift + left-click on an ingredient that a merchant is selling to transfer the whole stack to the trading area.
Ctrl + scroll wheel on an ingredient that a merchant is selling to add/remove ingredients from the trade area.
Right-click on a potion to instantly put it on the scale for sale.
R to open recipe book.
L to open legendary recipes.
G to open Alchemist's Path.
T to open Talents.
F5 for quicksave and F7, F8, or F9 for loading your quicksave.
Alt + Enter to switch between fullscreen and windowed mode.
Ctrl + L or Shift + L for changing the game language.
Ctrl + M to mute/unmute the music.
Ctrl + S to mute/unmute the sound effects.
Left-click on your potion symbol on the alchemy map so it centers on your screen.