[xwiki-users] Vote / Favorite feature on XWiki pages ?

Hello, Is there any way (by default or with an Extension) to add a kind of "vote" on each XWiki page? Vote will be opened to signed-in users just like they put a "+1" on Facebook. Then when reading a page, a user can know if content has been appreciated. thanks for your answers, regards, PS : what I need is a simple number on each page. I agree that comments are already a way to give an opinion on a XWiki page.