Command+Shift+3: takes a screenshot of the full screen.
Command+Shift+4: brings up a selection box so you can specify an area to take a screenshot of.
Command+Shift+4, then spacebar, then click a window: takes a screenshot of a window only.
Save file to your desktop
⇧-⌘-O -- numbered list
⇧-⌘-L -- insert table
⌘-{ -- align left
⌘-} -- align right
⌘-| -- center
⇧-⌘ X -- encrypt selected text
⌘-K -- add link
⌘-F -- find within note
⌘-S -- save