Hot Apps will feature 5 of the hottest apps each week for the Windows Phone 7. In this episode Laura takes a look at:

• Hydro Thunder GO
• DNA Roulette
• Easy Animator
• Apple Bin
• Grandma's Secrets

Search extras allow applications to integrate and add value to the search experience in Windows Phone.  For example,  after and finding a movie, search extras can launch the iMDB application to see reviews, buy tickets, etc.)

In this episode of the Inside Windows Phone show, Jared Brown ( Program Manager responsible for Search extras and Bing integration on WIndows Phone)  introduces the feature end-to-end, first with some demos and then with a walk through on how an application integrates with extras.

Relevant links:
MSDN documentation for search extras (has the doc mentioned in the video) 
Code sample for a search extra - you can use this in emulator.  Do a search for electronic (e.g. HDTV 52 inch). 
Jaime Rodriguez's blog