This week's book giveaway is in the OCAJP 8 forum. We're giving away four copies of OCA Java SE 8 Programmer I Study Guide and have Edward Finegan & Robert Liguori on-line! See this thread for details.
I'm not sure I understand the question. Are you looking for examples of what you can do with Flex (in which case this is good) or are you looking for high profile sites that use Flex (in which case the Flex homepage mentions some). Or are you asking about site that use Flash well (its far harder to know if they use Flex well without having their source)?