I recently had the chance to preview a new book that will be published in just a few weeks. The book, Developing Microsoft SharePoint Applications Using Windows Azure, by Steve Fox, dives into the many possibilities how you can leverage Azure components from within SharePoint. Steve explores things like using the service bus, SQL Azure, Windows Azure, Access Control Service, claims and the Azure blob storage.
As someone who's spent a little time with Azure this is one heck of a resource. Some things I've played with a bit but those I haven't spent time with are covered in great depth with good details to get up to speed. I really like how Steve has filled the book with a ton of references to other resources within each chapter but also at the end of each chapter for further reading.