I like a failed breakout for a reversal signal, very effective.
However, after the "flash crash" Schizo posted an ES chart to explain for me a gap in price and right away I saw a clearly definable chart pattern that I've since added to my arsenal.
I like F/U Candles (otherwise known as Morning Stars, but it seems like it's just a candle giving you the finger) and Up Yours Candles (otherwise known as Hammers, basically an F/U Candle upside down)