There is an unlimited number of ways to create amazing looking effects using Photoshop and its filters, let me show you how to create a mysterious looking one from scratch.
If you don't have installed program for editing PDF documents on your computer, then you can use web application PDFescape which allows you to edit your documents in your browser.
Google Docs or these days Google Drive can make collaborating with your colleagues or friends much easier by sharing Google Document, Spreadsheet, Presentation, Pictures or a whole folder.