This information was taken from the Wall Street Journal.

 The following companies just filed for Bankruptcy:

Hollywood Video
Levitz
Sharper Image
Performance Team Freight
Linens n Things
Circuit City
Bed, Bath and Beyond

When a retailer files for bankruptcy, the company can't redeem gift cards unless the bankruptcy judge gives them permission.  So if you have gift cards from the above list use them ASAP, they will not be valid for much longer.