Mashup Startup Infrastructure

Web services have brought down the cost of starting a startup to very very little. It's finally possible to focus on a good idea and the market, rather than wiggling about with getting the tech infrastructure right. These are my top choices for web services to serve as startup infrastructure:

Manage customers with Salesforce
List products for sale on Google Base
Do transactions via Google Checkout
Sell digital objects with Amazon FPS
Store image files on Amazon S3
Do all computing on Amazon EC2
Realtime events: DimDim
Phone to web audio: hipcast?
MultiuserServer: http://www.smartfoxserver.com/