When you're on the road, if you bring your own laptop, you can't afford to install your own software, so you just stick with the basics. There will be times when you receive a PDF document by email and are asked to make a few changes. You may want to type up your own page, or add an index, then include this within the existing PDF document. However, you'll need a PDF editor to do this and you won't want to make a purchase to make this small addition.

Luckily for you, there is an online service, PDF Hammer, that will enable you to make changes to your existing PDF documents. You can simply import a PDF and then remove, add or shuffle existing pages, then simply export back to your computer and, hey presto, you have a professional PDF document with your own additions.

PDF Hammer link.