For some reason I thought the extension we requested in April was good for 6 months - but apparently you have to file your return by Monday night OR request a second extension (which is only for 2 months, due by Oct 17th). The second request is very simple, and you can do it online:
http://www.irs.gov/pub/irs-pdf/f2688.pdf
BTW - you do need an excuse for why you want a second extension, supposedly one that is generally accepted is, "Still waiting for information needed to file".