Decent brands to look for:
Bianchi
Bridgestone
Nishiki
Centurion
Miyata
Trek
Univega

Other brands where there are some gems, but a whole lot of mass produced, lower quality bikes:
Pugeot
Raleigh
Schwinn

Don't ignore the lesser known brands, either:
Kabuki (produced by Bridgestone?)
Shogun--I got a great deal ($65) on a Shogun 600: lugged, butted steel frame, shimano 105 "Golden Arrow" components, in good working order.