Awhile back the Swiss National Bank was trying to keep the CHF weaker than it naturally would have been against the Euro, so they started intervening when it hit certain levels. These could cause moves up to about 300 pips. This went on for about 18 month and was reasonably predictable. I traded the EUR/CHF during that time and made a killing. It is the only thing I have ever tried outside of news trading that has worked consistently. They stopped about a year ago so now its back to the news again.
I have not seen any other intervention that was so sustained and predictable.