One of the more intriguing aspects of Windows Phone 7 is its ability to link up with your Xbox Live gaming account. By accessing the Xbox Live hub you can view and interact with your avatar (optional extras will allow you to poke, prod, and shake you avatar), manage requests, access your game collection, and see featured games on the Marketplace. Most important of all, though, in time you will be able to play some or all aspects of the same games you play on your Xbox and have your progress sync across the two devices.
Obviously the scope for this is limited given a phone won't be able to play the latest and greatest shooters, but it is sure to prove a compelling extra for avid gamers and an interesting avenue for innovation for developers. Again this is something we've had limited chance to play with, but we were told that EA is now onboard and were shown a rather impressive looking version of The Sims running on a phone.
Not wanting to abandon its office centric roots altogether Microsoft has enabled support for Microsoft Office document viewing, editing, and creating. Word, Excel, PowerPoint, and OneNote are all available and as with much of the phone's other data, updates made to documents can be wirelessly synced with your desktop.
This was the aspect of Windows Phone 7 we had the least chance to play with, so can't really vouch for how easy the whole process is, but the integration is bound to be tighter than any third party attempts.