One of my pet peeves when working with FLA's is that there's no easy way of finding out what Flash version the file was saved for. Northcode has just released a great freebie called Flaver - it hijacks the FLA format, checks what version it was saved as and launches the corresponding version of the Flash IDE (if you have it installed obviously). Its a very useful little tool and seems to work very well, there's almost no additional wait in launching your FLA. A feature I'd love to see is, rather than automatically launching Flash, have it pop up a message stating what version FLA you're dealing with.