New to winphone what should I check out?

I posted about a week ago that I was thinking about picking up a cheap samsung focus for my mom to use because I figured it would be the easiest for her to understand coming from a flip phone. I've received the phone today and after a few reboot loops (wtf samsung) out of the box I managed to update it to 7.5. I want to use it for a bit before giving it to my mom so I know how everything works if she needs help so i've got it set up right now as if I was going to be using it as my phone.

What apps should I check out?

any hidden functionality or easter eggs?

any kind of shortcuts i should know?

I like the aesthetic of it all so far but that gutter along the side of the home screen kind of bugs me