As every aspect of our lives gets more dependent on technology and the Internet, it is becoming more necessary to protect our privacy. Very robust anonymity systems have been designed and developed towards this end. They are being adopted by a high number of users and are endorsed and enhanced by a large body of academic research. However, and regrettably, robust and irrevocable anonymity can be (and is being) used for dishonest purposes too. Besides the ethical controversy that this arises, it also penalizes people who really need and/or make good use of anonymity. In this talk, we review systems that attempt to address this issue without penalizing privacy, both as domain specific and general solutions, making use of cryptographic primitives like group signatures and blind signatures. In addition, and in order to maximize the practicality of these systems, we review proposals such as standard-like definitions and cryptographic libraries that could serve as technological foundation to build them. Finally, we point out interesting challenges for future research. One such line is the study of objective blacklisting for preventing abuse of authority when anonymity revocation is enabled. Other seemingly independent line is trust decentralization; however, its connection becomes apparent when realizing that decentralization may be essential to ensure that no abuse of power is possible.