This flickr set contains logos from an out-of-print book, World of Logotypes. The 70s really created some simple yet beautiful logos using only geometric designs and interesting fonts.
They remind me of a quote I saw on the windows of Design Within Reach in Washington DC. "An interesting plainness is the most difficult and precious thing to achieve." - Ludwig Mies Van der Rohe
The Mountain Shop
Eastern Business Systems
Found via Dark Roasted Blend, one of the top 50 Blogger blogs.