This is a folder action handler that waits for file(s) to finish writing to the folder you attach it to. It calls my isDone() handler.

OS version: OS X

-- written by Jeff Case 2004
property LSreturn : ""
global CurrentFileSize, LastFileSize, StillBusy, StillGrowing
on adding folder items to this_folder after receiving added_items
		-- get the name of the folder
		tell application "Finder"
			set the folder_name to the name of this_folder
			-- find out how many new items have been placed in the folder
			set the item_count to the number of items in the added_items
		end tell
		ProcessAddedItems(this_folder, added_items, item_count)
	end try
end adding folder items to

on ProcessAddedItems(this_folder, added_items, item_count)
	-- loop through the files looking for finished files to process
	repeat with x from item_count to 1 by -1
		set File2Check to (item x of added_items) as string
		set AppleScript's text item delimiters to ":"
		set TheFileName to text item -1 of File2Check
		set AppleScript's text item delimiters to ""
		set LastFileSize to -1
		set Ready2Rock to false
		--loop waiting for the file to finish writing
		repeat until Ready2Rock is true
			-- modify the path accordingly - point to isDone().scpt on your machine 
			set testResults to run script alias "OSX:Users:ByteJockey:Library:Scripts:JScripts:isDone().scpt" with parameters {File2Check, LastFileSize}
			set CurrentFileSize to item 2 of testResults
			if item 1 of testResults is true then
				set Ready2Rock to true
				set LastFileSize to CurrentFileSize
			end if
			-- Wanna monitor the progress??
			-- un-comment this block of code
			set AppleScript's text item delimiters to return
			tell me
				display dialog (TheFileName & return & testResults) as string buttons {"OK", "Cancel"} ¬
					default button 1 giving up after 1
			end tell
			set AppleScript's text item delimiters to ""
			delay 1
		end repeat
		-- now that the file has finished writing,
		-- process the file while it's in this folder 
		-- if the file is so big another move would
		-- require another isDone() check
		tell me
			display dialog ("The file: " & return & return & TheFileName & return & CurrentFileSize & return & return & " is ready to process.") ¬
				buttons {"OK", "Cancel"} default button 1 giving up after 2 without static
		end tell
		-- then move the file to a "done" folder
		-- so the folder action can pick up
		-- a new file with the same name 
		-- because Folder Actions don't "see" overwrites
		-- only new files added are acted upon, not updates or overwrites
		--            tell application "Finder" to move alias (File2Check) to folder "path:to:done:folder:" -- intertpret as necessary
	end repeat
end ProcessAddedItems