Graphical screen lock pattern instead of PIN code
I think WP7 contains a superior user interface to other mobiles OS's.
However the screen lock code seems out-of-date and sub-par to the rest of the interface. Android allows you to setup a graphical pattern, for example, while WP7 only allows you to enter a PIN code.
A graphical pattern is more practical and user friendly that a PIN code.
I don't think this is a difficult thing to implement and would improve the user experience.
Great suggestion, but these are consumer features – and not developer platform suggestions. As such, declining this idea to give you back your developer platform votes.
You can submit and vote on consumer features at the Windows Phone Feature Suggestion Box here http://windowsphone.uservoice.com
Make it just like Windows 8!