The Command Syntax Help dialog can give you a short overview of all currently available scripting commands, global variables and pick-pocket-item types/subtypes. Use the three radio buttons on the bottom row to select between the different tabs.
Note that the Command Sysntax Help might look different depending on from where it was called. The help dialog will only show you the items available in the tab from which it was called. (Some commands are not available for pick-pocket-item databases.)