There are several reasons why you probably do not want to share too many aspects of your life with Google: It has a near monopoly in several aspects of the Internet, and has its hands in many others: search, advertisement, calendaring, cloud storage, social media, news, e-mail, maps, online office …
This site lists competition. And by using several of these, you give Google the chance to gain new insights about you by combining data from several services.
del.icio.us-alternative mit einigen zusatz-funktionen Diigo will let you highlight sections of a page, post a note about why you needed it, make it public or private, send it to friends and so on. As they say, they allow you to do everything you could on