Using the Command Launcher
One of the most useful functions of ImageJ is the Command Launcher (also known as Command Finder). The keyboard shortcut is ^ Ctrl+L (or ⌘ Command+L on Macs).
Once the window opens, just type part of the menu item you want to launch, and it will show you a list of commands that match that substring:
If you are not quite sure about the spelling, just click on the Fuzzy matching checkbox:
If you want to know what menu the entries are in, or from which .jar files they come, enable the full information: