For the past several months, I've been running three websites on a pair of extra small instances, including albahari.com, linqpad.net and the LINQPad licensing server (which uses LINQ to SQL). The trick is to serve large static content directly from blob storage so that it's not subject to the 5MBit/second I/O bandwidth restriction. And I've never got anywhere close to running out of memory.
A pair of extra small Azure instances is a great alternative to shared hosting when you need better reliability, security and performance.
Edit: close to a year now, still no problems with multiple websites on Azure. I will never go back to shared hosting.
