Associate a document with a task

Currently in GTG, users can add tasks, subtasks, tag them, color them, etc. However, they cannot associate pieces of data with a file. I'd like to be able to associate a webpage, email, document, tomboy note, or folder with the task (possibly drag-and-drop?). This would be a great feature because I often find myself adding tasks like "Learn PyGame", and I want to be able to attach a URL to the PyGame website, to a few pdf tutorials on my hard drive, and a folder full of code for a game I'm writing with PyGame. This could be implemented by adding links to the file/folder/url or the attachment method Evolution and KOrganizer use for their To-Do list functionality.