JIM WEISBIN  I bought FieMagnet and downloaded the "uploader" program (which is supposedly what's listed here?). It all works fine on iPhone 3.0.1. The latest uploader program shows version 1.2, this is listed as version 1.3.1, not sure why the discrepancy.  
(Version 1.3.1)

JAN_RYBAR  Air Sharing does the same and you need only iPhone app and Finder. It's free now, after several days it will cost 7 $. Try and compare. - http://www.avatron.com/products/  
(Version 1.0.1)

ODYSSEUS  DiskAid (for Mac, not iPhone) is free and makes it easy to transfer files to and from your iPhone via simple USB connection. It doesn't preview the files on the iPhone like this, though.  
(Version 1.0.1)

EVERLAST_34  Positive: All in all, File Magnet works really well. If you want to transfer files to your iPhone, so you can look at them later, then this is definitely worth 5 bucks to you.

Negative: Be sure you have wifi setup. This prgram needs a wifi connection to transer the files. Also, if the files are too big (50+ pages) then File Magnet may not be able to load them on your iPhone.  
(Version 1.0.1)