Although source code is generally represented at the granularity of a file, software developers rarely work with code at this level. Developers work with interrelated fragments, distributed across numerous files, usually representing some cross cutting concern or task. What more, developers have few tools to help them gather and track these interrelated fragments and other notes, other than jotting them down in a notebook or just remembering them. Not only does this make it difficult to get back on task after interruptions, but it also makes it difficult to share tasks with coworkers.
Jasper is an Eclipse plug-in that allows you to gather three types of information into a single document: references to code snippets, textual notes, and links to parts of web pages. In doing so, Jasper allows you to keep track of your development tasks in a clean and distinct fashion, much like bug reports are a central source for information about a particular bug. These documents can then be stored for later and shared with colleagues, perhaps by attaching them to bug reports to document the results of some debugging work.
Full details are available in the paper:
Coblenz, M. J., Ko, A. J., Myers, B. A. (2006) JASPER: An Eclipse Plug-In to Facilitate Software Maintenance Tasks. Eclipse Technology Exchange Workshop at OOPSLA 2006.