The EFF points out problems with California's Proposition 35, which would, among other things, require registered sex offenders to “disclose Internet activities and identities”:
[...] Proposition 35 would force individuals to provide law enforcement with information about online accounts that are wholly unrelated to criminal activity – such as political discussion groups, book review sites, or blogs. In today’s online world, users may set up accounts on websites to communicate with family members, discuss medical conditions, participate in political advocacy, or even listen to Internet radio. An individual on the registered sex offender list would be forced to report each of these accounts to law enforcement within 24 hours of setting it up – or find themselves in jail. This will have a powerful chilling effect on free speech rights of tens of thousands of Californians.