Found 2 great webpart which can be used for learing purpose, you can download it from http://www.codeplex.com/smarttools

  • What’s New: a customizable web part that can display a list of recently added or changed items of a SharePoint site or site collection
  • Autocomplete Text Field: a field that allows users to pick items from a list by making use of an AJAX autocomplete text box. See the Autocomplete Text Field in action: screencast


What’s New Web Part screenshot:


Autocomplete Text Field screenshot: