I had the idea for PornoTube (YouTube for Porn), but couldn't live with not being able to tell my girlfriend's parents what I did ;-)
Shame, it's now Alexa rank 203 - probably 10 times the size of twitter. :(
Shame, it's now Alexa rank 203 - probably 10 times the size of twitter. :(
The barrier to entry you mentioned keeps everyone away though...