If you've ever wanted to make notes or markups on a PDF file but you don't have the full version of Adobe Acrobat, check out the free PDF-XChange Viewer. If you have ever filled out an online application using a PDF file only to discover at the end of the 10-page document, that you can't save it, try using PDF-XChange next time. The free application is an excellent replacement for the full-blown version of Adobe Acrobat.
PDF-XChange allows you to type text using the typewriter tool (great for filling out and saving those long PDF applications--even PDF's that don't have forms). The program also allows you to draw comments, sticky notes, lines, objects, and mark and highlight text. It is great for marking up CAD drawings or other design documents. I found PDF-XChange easy to use and I'm sure glad I found it! (Sources: Tracker Software Products, Lifehacker)