The Pension Benefit Guaranty Corporation, in conjunction with the Pension Action Center at the Gerontology Institute, University of Massachusetts Boston, published this booklet in August 2002: Finding a Lost Pension (39 pages, PDF), which will assist you in planning and conducting a search for funds that are in your name, or funds which may be payable to you as a surviving spouse. Worth a look, and thanks to Michael Ravnitzky.