Office Depot is still around.
Dean Foods is still around
Frontier Airlines was spun off and sold again back to Denver stockholders - it still operates.
Sara Lee is still around - in fact, moved their HQ to Broomfield, Colorado and renamed Hillshire Brands
Borders shut down July 19, 2011
Gateway - Part of Acer - brand still exists
DollarThrifty - It's still up for sale - Hertz shows interest, but sounds like Dollar is still in business.
Answers.com - still alive
E*Trade - still alive