Basic editing

⌥↓    Move line down
⌥↑    Move line up
⇧⌥↓   Copy line down
⇧⌥↑   Copy line up
⌘↵    Insert line below
⇧⌘↵   Insert line above
⇧⌘\   Jump to matching bracket
⌘]    Indent line
⌘[    Outdent line
⌘/    Toggle line comment

Multi-cursor and selection

⌥•    Insert cursor
⌥⌘↑   Insert cursor above
⌥⌘↓   Insert cursor below
⌘U    Undo last cursor operation

Search and replace

⌘F      Find
⌥⌘F     Replace
⌘D      Add selection to next find match
⌘K ⌘D   Move last selection to next find match

More shortcuts…