XCrowd
On July 2nd, 2013, xCrowd announced their intention to produce a custom Bitcoin mining ASIC.
Although not formally canceled, no substantial post was made to its announcement thread by xCrowd since August 26th, 2013.
As of June 6th, 2014, the original BitcoinTalk Forum account used by xCrowd appears to be in use by a different person, based on the changes in writing style and interests.