I might bitch about eating our own dogfood, but a lot of the time it's actually pretty damn tasty.

For example, I can't remember how I ever used a laptop without the combination of folder redirection and offline files. Microsoft's technical support staff use folder redirection to give each of us a gigabyte of storage space on a central server, mapped to My Documents. This is pretty nice in itself - since they back up that server, there's no need for me to bother with all the hassle of backing up my personal machines. In this sense folder redirection is “just” a personal share on a server.

Combine folder redirection with offline files, however, and you've got a killer feature for laptop users. When my Tablet PC is on the network, I've got full access to My Documents. Then I go off the network - and I still have full access to all those files, stored locally (and transparently) under C:\WINDOWS\CSC. I can modify them to my hearts' content, knowing that when I reattach to the network mobsync.exe will automatically detect this and let me synchronize all changes. And since I'm the only one touching those files, and I'm rarely working on more than one computer at once, synchronization conflicts (when it asks you to choose whether to keep one or both versions) are equally rare.

Notes and gotchas:

• Even if an application doesn't normally keep its state in My Documents, you can often move it there. My Internet Explorer favorites and FeedDemon cache files live quite happily in My Documents, so that they're always synchronized across machines. Dare Obasanjo has just found out how sweet RSS feed synchronization is while hacking on the next version of RSS Bandit :-)
• You can set up synchronization to happen automatically, but this can bite you in corner cases. Instead, I set it up to never synchronize automatically, do an explicit synchronization before disconnecting, and then let it remind me to synchronize on reconnection. Works every time.
• In particular, you almost certainly don't want to synchronize automatically if you've just connected to the network over dialup. Use that narrow straw to check your email, but keep your documents offline for fast local access.
• If you're an MSN subscriber, you can even synchronize to a web folder on the internet. Omar Shahine shows you how (and gripes about folder redirection - hey Omar, try my tips above!)
• The synchronization manager will refuse to let you mark database files as “available offline”. This particularly hurts for Outlook's .pst archive files.

Any tips that I've missed? People seem to either love or hate offline files. Me, I just remember the hell of roaming profiles…

Updates:

• Yup, I missed one - the other big win of folder redirection is when you combine it with shadow copies on the server.
• Rich C left a pointer to a knowledgebase workaround so that you can sync Outlook .pst files as well.
• Omar Shahine found a solution to his pain, using the undocumented mobsync /logon for a quick sync that just pushes files you've updated on your laptop back to the server, and mobsync /logoff for a full sync that also pulls any files that have changed on the server.
• You can find more posts and questions about offline files in my “Offline Files” category.
• Larry Osterman Raymond Chen points out more things that can go wrong with roaming user profiles.