Carmen Delessio's Amazon SimpleDB is an app targeted at developers, but its functionality could be popping up soon in an app near you. It illustrates how Android can take advantage of could services.
This video focuses on voice recognition, while another showcases database searching. And while perhaps a bit arcane to the average user (me included) this demonstration translates to some very practical daily use. Social networking, anyone?
The developer is also working on a Facebook photo app, and plans to enter the second Android Developer's Challenge. Follow Carmen's work and get deeper technical info at Talking Android.