The Guardian of London has established an Interactive Guide to "China's Detained and Missing", providing information about 43 dissidents and activists. Examples:
Ni Yulan (Beijing): Rights lawyer disbarred and beaten after defending residents against forced demolitions. Reportedly detained by police on 7 April; police believed to have notified family she is at Xincheng detention centre
Dong Jiqin (Beijing): Husband of rights lawyer Ni Yulan; reportedly detained by police on 7 April; police believed to have notified family he is held at Xincheng detention centre
Zhu Yufu (Guangzhou): Pro-democracy activist, detained by police 5 March; then formally arrested for 'inciting subversion of state power'. Has been jailed twice, serving 7 years from 1999 for involvement with the China Democratic Party