Quick AppleScript to export all your notes from Apple's built-in Notes.app application

export_notes

tell application "Notes"
  set note_body_list to (get body of every note)
end tell
set note_count to (count of note_body_list)

set blah_folder to choose folder
set blah_path to POSIX path of blah_folder

repeat with i from 1 to note_count
	set filename_string to ((blah_path & "note" & (i as string) & ".html") as text)
	try
		set newFile to open for access POSIX file filename_string with write permission
		set string_to_write to (get item i of note_body_list)
		write string_to_write to newFile as text
		close access newFile
	on error
		try
			close access (POSIX file filename_string)
		end try
	end try
end repeat