Windows Phone 7 continues to gather high profile applications, and the latest one I noticed (which has however been in Marketplace for a while) is a Ustream client for Windows Phone 7.
Window Phone 7 is only the third mobile OS to get a Ustream viewer, with Symbian, Blackberry and webOS all being without. The app joins other high profile services such as Slingplayer, ebay, Netflix, Amazon Kindle and others as examples of applications which makes Windows Phone 7 a first class citizen despite such small initial numbers.
The Ustream client can be found in Marketplace here.
Is there any other major web service which is missing on Windows Phone 7? Let us know below.