I was impressed with the MAT tool that encapsulates all the information one has to be aware of, before attempting the application migration to Windows Azure platform. The tool addresses migration considerations including app server, database, integration, security and instrumentation for .NET as well as non .NET platforms like Java and PHP. After answering a series of simple binary questions, the tool will generate a nice report which hints at the amount of work involved for the current application migration or the architecture considerations for a new application.
The MAT tool runs only on Windows as it is rich client application updated through ClickOnce technology. Initial tool download can be done from: http://matclickonce.blob.core.windows.net/app/publish.htm .