Trails is a Firefox extension, designed for collecting, editing and organizing fragments of text and images to complement their main application for research. It's meant for quick and easy data collection. The data are stored in small booklets, of which one can create and maintain as many as one needs. It does not require the user to re-structure the research document manually by saving the collected fragments of text and images.
The key point of Trails is, however, the ability of transforming combined website fragments (text and images) into printable booklets. If you don't need printed booklets, I would not recommend it. It is a bit cumbersome.
1. This is an edited version of the description of Trails, found at the Website referenced above.