Not AX related, unless you want to develop a 10-minute Windows Phone 7 app (see what I did there?).
In any case, came across this interesting post through twitter, which highlights some great tools for Windows Phone 7 developers. The Silverlight Spy looks really interesting, it's somewhat like UISpy, but for Windows Phone 7 and some special features.
For this and other interesting WP7 development tools like the Isolated Storage Explorer and Metro Grid Helper, check out this blog post on Diary of Ninja.