1) Syncing Favorites
This has been one of those problems that has plagued man since the dawn of the browser.  I've never been happy with any of the existing solutions... until now.  IE favorites are just some files in a directory and Mesh syncs directories.  Sounds like a winning combo to me! 

First, add your favorites folder to Live Mesh.  This is as simple as finding your Favorites folder and adding it to Live Mesh. 

Then on every machine on which you want to sync the Favorites, click on the Live Mesh "Favorites" shortcut that shows up on your desktop.  You will be shown a window like the one below, asking you where you want the synchronized files to end up.

You want the files to synchronize to the folder that IE uses for favorites, so click Browse and find it:

Since the folder already exists you will get a warning about merging the two directories.  To make things easier I simply delete everything in the local Favorites folder first and then allow Mesh to merge the directories.

And that's it!

2) Cross domain development

Lately I've been doing development across two machines, one joined to a domain and the other joined to a workgroup.  I wanted to remotely debug from my domain joined machine, but hit all kinds of permissions problems.  I'm sure there was a way around this, but it was faster to simply mirror my entire source tree between the two machines using Live Mesh.  From there I just used Remote Desktop to log into the workgroup machine and debugged locally using Visual Studio.  With LM syncing all of the files I was able to make fixes on both machines as I moved back and forth between instances of Visual Studio.  Very cool.