To create the perfect suite or set of tools that I need to operate on a daily basis I need different applications that interact and operate on a common standard and interface.
I need to be able to try different perspectives and approaches.
If an application doesn't work for me I need to be able to say NO! This doesn't work dammit, and show me others like it so I can try more.
I don't want to have to worry about my data, it stays with me!
I fire up the new application and it works for me, and my data is all in there.
Sure the bigs boyz can fight over who will give me my base platform. Google works for me, but Yahoo may for you. Windows Live maybe be a better option.
However you need to let vendors share their warez and offer them to me in a safe environment. They can peddle whole systems or just objects and features. Maybe they can perform a service for me. Something like Salesforce Appshare with a more Firefox Add-on feel.