A nicely organized timeline for the month of April published by hackamgeddon.com depicts the most remarkable cyber-attacks that took place during this month. The information presented in a table format includes the date, authors of attacks when available, target victim or victims, target sector, attack type and motivation behind each attack. In fact, apart from being a good motivator hacktivism targets multiple sectors and not just governmental bodies.
1-15 April 2013 Cyber Attacks Timeline - http://hackmageddon.com/2013/05/01/1-15-april-2013-cyber-attacks-timeline/
16-30 April 2013 Cyber Attacks Timeline - http://hackmageddon.com/2013/05/05/16-30-april-2013-cyber-attacks-timeline/