PeopleEditor is a nice webcontrol for picking people. To add it to your webpart or page is easy: But there is more we can do with pickers in Sharepoin. We can define our own pickers. Jeremy Luerkens gives one such example and a code sample (!). Another example can be found in Sharepoint as a Development Platform (p. 661), even though it misses the important class BookQueryControl. Just to start I made a book picker (I simplified and changed the idea provided in the book).