Custom Control

How to create custom control

http://www.silverlightshow.net/items/Creating-a-Silverlight-Custom-Control-The-Basics.aspx

Zoom control

http://zoomcontrol.codeplex.com/releases/view/35970

Gauge

http://www.codeproject.com/Articles/38361/Circular-gauge-custom-control-for-Silverlight-3-an