Useful Links

http://aaclage.blogspot.ca/2013/09/example-custom-ui-metro-style-tiles.html
http://karinebosch.wordpress.com/sharepoint-controls/peopleeditor-control/
http://www.sharepointanalysthq.com/2014/05/custom-webpart-editor/
http://fahadzia.com/blog/2009/08/peopleeditorpeoplepicker-control-as-web-part-property/