MS Outlook has so many shortcomings (ie search!) - but for those of us who live on it for work, the biggest struggle is its inability to easily navigate through contacts, conversations and trends. Xobni tries to tackle those issues as a data-driven plugin for Outlook.
Xobni has been well received by the blogs and among everyone I've interacted with (although not a single person has pronounced their name, inbox spelled backwards, the same... which spells branding trouble). And while Xobni is off to a good start, there are still a few shortcomings that I hope that team is working on:
* Customization: I want to change the look, the amount of content displayed and the default content buckets. Currently, nothing is customizable... a bad sign for any supposedly-viral, consumer based-company
* Move beyond Outlook: Like most people I know, I have multiple email accounts -corporate, personal, personal businesses, etc.... and they all live in different destinations (outlook, gmail). I want a service that will operate between my email accounts and providers. I'd pay big for that too...
And the best solution for that killer app lives on my blackberry. Think about it - it houses every email I send / receive, all of contacts, all of my phone calls and sms'es... My blackberry has the data necessary to create my own social network using my communication behaviors across numerous accounts and mediums.