Here are a couple of links to some very useful tips and tricks pages for WP7. I had been trying to figure out how to insert the cursor into the middle of a word to edit it when composing a text or email and one of the tips was for exactly that! Also another one that wasn't aware of was that you can change the background image on the home screen Pictures tile. I made mine one of my favorite pics I ever took (a shot of the Lincoln Memorial in DC lit up against a darkened nighttime sky. It's perfect for the portrait orientation of the tile!).
http://www.intomobile.com/2010/11/12/top-tips-tricks-windows-phone-wp7/
http://www.pocket-lint.com/news/36413/72-windows-phone-7-tips
