Air Sharing, actually does the job quite well in addition to its over the air file transfers. $4.99 is great for all of the things that it does!
I personally fid Air Sharing a tad on the slow side, but so are most of them. I am about to delete air sharing as i have found a suitable replacement - TextGuru not only can you see PDF's but you can make your own text docs and html and all sorts of things. I can download pdf's or most any link/doc from the web (can't do in Air sharing, but can do in folders also) Text Guru has copy and Paste features - I use the app for all my notes. Works great also for a list of phone numbers that you don't use enough to want to clutter your address book but may use now and then - just click the link when web preview is enabled and it calls.
It supports file organizing - I can make new folders and copy entire doc into that folder for better organization.
It has several way to get docs onto the iphone and supports many formats. I got it when it was $.99 but it is well worth the asking price now (I think they ask $4.99)
Over all a great app!! Great support - constantly adding features and bug fixes.