what i think is the next ebay in the making: credential management. Microsoft passport was brilliant but its closed source and hierarchical. a distributed database like DNS with an open standard for authentication is needed. the liberty project and SASL are the first things that come to mind.
MyUID is a half-assed but interesting attempt at an "open ms passport". even though the standards are open and free, people will still want a 3rd party service to hold credentials and be easily referred to when entering secure websites. maybe a large free project will emerge that most people will use, or maybe a pay service will emerge. notice there is no large free ebay service. Of course many people will want to run their own credential server but many people as evidenced by hotmail and yahoo, will find it most convienent to use a 3rd party service.