I use Workflowy and paste in Google Docs/Drive links to any file I need to reference. I love Workflowy's flexibility - it's amazing for everything from task management to taking meeting minutes to brainstorming... and then organizing it into one cohesive system.
+1 for Workflowy. I started using it a few weeks ago; I like it more with every passing day, especially 1) the simple UI, 2) easy tagging, 3) easy searching, and 4) the ability to click on an outline level to make it "the page." Yeah, this is off-topic, but I really hope the Workflowy crew prospers so they can keep improving the service.
