Windows Live for Windows Mobile
Windows Live was launched without much fanfare and is built into most WIndows Mobile 6 phones (some carriers replace it with their own email clients). I can't live withour the Local Search - it is awesome!
Besides being a great example of what a smart client application can do (fast response, local data een when there is no connection, etc.) I find Live Search tremendously useful when on the road - locally or when traveling. I use it to find addresses, directions and restaurants as well as to get real time traffic updates.
I am not a big user of messenger or spaces but I do find Live Mail very convenient - I get Push HTML email from my Hotmail account on my phone.
You can learn more about Windows Live search at this new microsite www.windowsmobile.com/livesearch