Keystroke commands for open recent
I have used FastScripts to assign a shortcut to this script:

tell application "System Events" to tell (process 1 where it is frontmost)
    tell menu bar item 3 of menu bar 1
        click
        repeat with x in {"Open Recent", "Open Recent File", "Recent Projects", "Open With"}
            if exists menu item x of menu 1 then
                click menu item x of menu 1
                exit repeat
            end if
        end repeat
    end tell
end tell


It opens an Open With menu in Finder and a menu for recent files in other applications.

There are other ways to assign a shortcut to a script using Quicksilver, Alfred, etc.