I created a "Conditional Lookup" control for SharePoint 2010. With this you can connect two lookup fields controls on list forms to fill the second control with values depending on the selected value in the first control. There is a demo inside.

This example will show you how to create a custom list form for SharePoint 2010 in Visual Studio 2010 using SharePoint Designer 2010 and VS2010... See my blog for a "Walkthrough": http://ikarstein.wordpress.com

SPManager is a helper class to get SPSite and SPWeb. Stop thinking about when to dispose or not to dispose them. It will do the job for you.