In short, lots. I think Xobni's person-oriented metaphor is a very strong one. It doesn't replace Outlook's UI, but it does add a lot of value to it. In Gmail

In short, lots. I think Xobni's person-oriented metaphor is a very strong one. It doesn't replace Outlook's UI, but it does add a lot of value to it. In Gmail, I end up with dozens of labels and filters putting mail in each of those labels. Many of them basically group mail by people, which is Xobni's strength. I love the idea of seeing that person and all conversations you've had with them separated out without having to create that through a label system. It's such a common thing to want to reference, but not as easy as it could be in Gmail. It's also great to have quick access to files sent by that person, separate from emails. Digging through emails to find the right one that a file attachment was attached to is no fun in Gmail or pretty much any other mail program. Xobni wins on this front big time. Another is seeing relations between people. I do this by filtering groups (usually by common domain, but then there are exceptions for personal email addresses too) into their own labels like "Client X" and "Client Y" for my most active clients, since keeping them all in one stream is just too much to manage. But being able to quickly drill down to Joe who works with Steve when Steve mentioned something Joe was supposed to send you would be really nice. Another Xobni win there too. Gmail Labs sounded like a good idea, but while a few are pretty useful, most of the options in there are a joke. A snake game? Come on. Randomized signatures? How about selectable signatures already? They really need to start thinking a bit bigger to continue improvements. Gmail is far from perfect, and while Xobni isn't a complete client unto itself, it is a nice addition to one to be sure.