very nice and usefull for sharepoint 2010 blog

http://johanolivier.blogspot.com/2010/08/sharepoint-2010-ribbon-enabled-web-part.html

http://virtualizesharepoint.com/category/sharepoint-2010-search/

http://www.sharepointkings.com/2010/09/sharepoint-cascading-drop-downs-using.html