Little icons appear next to the names of some people. Here is what they mean:

The green tree means this person is an ancestor of the website compiler / collator
Paperclip means this person is considered 'Notable'
The blue tree means this person is a descendant of the compiler's oldest relative with 'Y' DNA
The silver star means that this individual is a member of the Dowlings of the South list for North America
The envelope means this person had been edited in the last seven days