Mark as Done / Remove from Agenda - keyboard commands

Here are the shortcuts:

Shortcut Command
⇧⌘ U Mark as On the Agenda / Remove from On the Agenda
⌘ ⏎ Mark as Done / Undone
⌥⌘ ⏎ Mark as Done Completely (also Removes from On the Agenda)
⇧⌘ K Pin to Top / Unpin from Top
⌥⌘ ↑ Collapse
⌥⇧⌘ ↑ Collapse All
⌥⌘ ↓ Expand
⌥⇧⌘ ↓ Expand All

For the entire list, see Introducing Agenda - #8 by system