Diamondback has never been a company -- just a brand name owned by an importer who slaps the name on decals. When Diamondback bikes first came to market in the '70s, they were BMX bikes imported by the same company that sold Centurion-branded road bikes. A few sales later and the brand now belongs to Accell, a Dutch company who also produces Raleigh and Redline bicycles for the U.S. market. But anyway, yes, the Diamondback name has been put on some decent bikes recently. The Podium series road bikes aren't bad, for example -- especially for bikes being sold through 'big box' stores.

I have a Diamondback Steilacoom cyclocross bike and its frame made by Kinesis. There's even a decal on the frame that says so. Kinesis is a Taiwanese company, founded by former Giant employees, but they have a factory in Guangzhou, China. According to Wikipedia, Kinesis builds frames for the following brands (and possibly more): Diamondback, Raleigh, Felt, GT, Schwinn, Jamis, K2, Trek, Kross, Kona, and BikesDirect.

Luxottica, an Italian company, has a near-monopoly on eyeglasses worldwide, commanding something like 80% of the market. They've been gobbling up or squeezing out competitors for years, including their acquisition of Ray-Ban in the '90s. Oakley held out for quite a while, but they got bought out by Luxottica a few years ago.