ATG (http://www.atg.com) is a frameowrk, a platform and a solution for content presentation and management, personalisation, e-commerce and customer relationship management.
Which free and open source frameworks or products would you recommend to replace the basic functionality it provides?
In the spirit of Stack Overflow, can you answer with one item in each answer and use the voting rather than duplicating someone else's answer.
I have started with some answers