Ask.fm - Curious? Just ask! Openly or anonymously.
Tellonym - Tellonym is the most honest place on the internet.
Retrospring - Q/A based social network
Zaqa - Zaqa is a Question & Answer based social networking tool.
Whisper.sh - Whisper is the best place to express yourself online. Connect with likeminded individuals and discover the unseen world around you.
NGL: Anonymous Q&A - Fresh take on anonymity!