Microsoft has released CTP1 of Project Houston for SQL Azure. Project Houston is a Silverlight web based database management tool that lets you manage and develop SQL Azure databases using a web browser. You have to go to SQL Azure Labs to access this CTP of the tool, but it lets you connect to your regular, production SQL Azure databases just like you can with the SQL Server 2008 R2 version of SSMS. Microsoft’s David Robinson has some more detail here.
I tried it out for a bit tonight, and the first thing I noticed was that the Silverlight control for the initial login screen does not let you paste the SQL Azure server name into the control. This is a little annoying, since SQL Azure has quite long server names! Update: It turns out you can paste into the Silverlight control, using Cntl-V. You just cannot right-click and choose paste from a context menu. I simply jumped to the wrong conclusion when I did not see the context menu.
Below, you can see the Start Page. The square box in the middle is actually a cube that you can spin back and forth with the arrows to either side. It displays different information on each side of the cube.
For day to day use, I think SSMS would be a better choice, but I could see some scenarios where a web based tool could be handy.