PDF995

Pros: more customization options, plus together with this you can get the free PDFEDIT995 with even more PDF editing tools!
Cons: shows annoying pop-up ads everytime you print to PDF!  and it can be confusing to install as you need to install something else (PS2PDF995?) to make it work!  lastly, like most of these freeware PDF creation tools, there are some custom paper sizes that this cannot print to.  for book-publisher-wannabes like myself, that's a bummer!

CutePDF and TinyPDF

Pros: no pop-up ads, therefore absolutely free!
Cons: fewer options compared to PDF995!  i also had a problem uninstalling TinyPDF one time.  lastly, like most of these freeware PDF creation tools, there are some custom paper sizes that this cannot print to. for book-publisher-wannabes like myself, that's a bummer!

the ronjie.com software essential vote: PDF995 if you don't mind those silly pop-up ads! otherwise, if you have money, go get Adobe Acrobat (not the reader) instead.

Microsoft SyncToy 2.0

Starting from the earlier versions of Windows, I have been using its Briefcase functionality to synchronize files between my computer and a second location (usually a second computer or a back-up drive), effectively creating a mirror and back-up of files important to me.  Briefcase has some limitations though, and sometimes in my experience, I have forever lost some files because of Briefcase.
Microsoft's software engineers who have created a series of very useful small programs (that Microsoft officially does not support) called PowerToys have now created what they call SyncToy which basically does most of what Briefcase does, only better.  It does just that: synchronize two files.  Is it a toy?  Technically, it is but for most of us, it can be very handy particularly for backing up files.
It has some limitations compared to Briefcase but with the problems I have encountered with Briefcase, I just tossed those limitations to my Recycle Bin.  Download SyncToy (version 2.0) for FREE.