I often find that there is a document that I want to keep with me to access later when I am away from my computer: on the road, at a deposition, in court, etc. The iPhone does a nice job of displaying documents such as Microsoft Word files, Microsoft Excel and PDF files, but the iPhone doesn't have any built-in ability to transfer such files from your computer to the iPhone. There is an inelegant solution -- you can send yourself an e-mail with the files attached and then access the e-mail from your iPhone -- but as you get new e-mails, your e-mail with the files attached gets harder to find.
The current solution for me is the app DataCase. It is a program that holds any kind of file that the iPhone can handle, and even allows you to create folders. So I can create a folder for the Smith v. Jones case and then toss in PDF scans of court orders, important Word documents such as memoranda, a Word document containing the names of all of the counsel in the case and the court docket numbers, etc.
Transferring a file to DataCase is very easy from a Mac: you simply start DataCase, then open up a window in the Finder and you will see your iPhone automatically show up in the list on the left of the window. There are a few more steps on a PC but it is still pretty straightforward: when you start the app, the screen has information at the bottom on how to access your files using Windows. You go to My Computer in the Start menu, then you type in the ftp information. (For example, as shown in the sample screen to the left I would type "ftp://10.0.1.196:2121") The DataCase website has videos that walk you through every step of the process on a Mac or a PC. When you try to access DataCase from your computer, your iPhone will first show an alert to confirm that it is okay to give this computer access, and then once you tap OK the computer is connected and can upload, download or delete files and create folders.
There are other programs out there that do the same thing, such as FileMagnet and Files, and you can click here to read a review of all three programs by Dan Moren of Macworld. DataCase is my favorite of the three, but they all seem to be good programs. If you don't mind keeping your documents on the Internet (which limits your access to those times when you have a WiFi, 3G or Edge signal), you could also consider a website such as Google Docs (which has a very nicely formatted version of its website for the iPhone). And there is another similar program coming soon that has my attention. On my previous phone (a Treo 650) I used a program from DataViz called Documents to Go to move files to and from my phone. That program even allows you to edit files, although in the many years I used that program I never once found a need to do so on my Treo. There is a teaser page on the DataViz website announcing that Documents to Go is soon coming to the iPhone. When it does, I'll certainly want to take a look at it and compare it to DataCase. (I've been a fan of DataViz's products since I used their MacLinkPlus program when I was in college in the late 1980s to translate documents on a Mac from Word to WordPerfect and vice versa.)
DataCase has lots of other features, although I don't really need to use them. For example, you can add photos, audio and video if you want, although I prefer to use iTunes on my computer and the iPhone's iPod and Photos apps to handle my audio visual needs. You can also set up public folders and private folders in DataCase, although again that isn't necessary for my needs.
Viewing documents on your iPhone certainly has its drawbacks. The iPhone screen is nice, but I wouldn't want to read a very long pleading on such a small screen. There is currently no ability to search document contents, so you can't quickly find that one paragraph in a brief that discusses a case. But DataCase is still useful when you want to take a quick look at a document but don't want to have to lug around the paper or your laptop. And whenever I travel, I print my travel reservations to a PDF file and then toss that in DataCase so that I have easy access to my reservation numbers, addresses, etc. if I need them.