What to do if you come across a document you don't have the program for? If it's a Word or Excel file this site will take care of it. (It also doesn web pages.) Just upload the file, enter an email address you can be reached at, and after a while (I didn't time it) you get a mail with a link to download a PDF file.

Probably not a good idea to pass sensitive data around like that, but it's god for manuals and such. I used it to convert the manuals for DNA and Popcorn.
(Of course if you do have sensitive data around chances are you know the creator and can ask them for a file in a different format, right?)