Must-have lesser-known Windows 8 Apps/Software + Tips/Tricks?

Hello Microsoft Tribe. After much consideration I have decided to get a Surface Pro. I know that it will be replaced soon due to its lack of Haswell, which is why I will be replacing it with an ultrabook once they are released during IFA. But for the meantime though, what do you, the wise people of the Tribe, have to offer? I know that I should install Chrome/Skype/Evernote (the usuals), but what hidden gems are there?

Thanks very much in advance!