Windows Phone users, what cool things can your phone do?

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I switched to a Windows Phone a couple of weeks ago and I feel that I haven't explored its full potentials yet. I was only able to synchronized my contacts list to their Facebook and Twitter accounts so it's easier to keep track of updates from my friends. I've also filled up the Pictures folder with some favorites and added a couple of play lists under the music + video section. I'd appreciate it if you could share ways you customize your phone. Thanks! :)