http://www.siliconinvestor.com/readmsg.aspx?msgid=23325768
According to Dick Arms, when we get readings like we have right now, a significant market bottom can be expected within 20-days. I think it's calendar days. I recall this working pretty well in 2001 to 2003.
In edit, in 2003 we still moved down for a couple of days after the first extreme reading.