Creating Collection Controls with Rich Design Time Support
http://www.divil.co.uk/net/articles/designers/collectioncontrols.asp
Codes available both is C# and VB.Net
Here is another one from MSDN
Developing Custom Controls in C# with Smart Device Extensions
http://msdn.microsoft.com/library/default.asp?url=/library/en-us/dncenet/html/customctrlssde.asp