There are many approaches to this issue, which after all is a common one whenever people are collaborating on documents. One of the particular constraints for some of us though, is that the solution has to be low-bandwidth, simple, and free (or at least very low cost). It simply isn't practical to be uploading and downloading a 20 MB file every time it is changed.
I've looked briefly at Google Docs, which works fine and would be my first choice for documents that don't have a lot of formatting requirements. Collaborators work (even simultaneously) on a document in Google's own format, stored in cyberspace somewhere, and that document can be exported when necessary to another format. Documents can be text (with pictures), spreadsheets, or presentations. Google Docs is free, doesn't require any setup, and lets users work online or offline (that is, you can edit documents even while not connected to the Internet, and they will be saved again when you are online).
Google Docs won't do what I need at the moment, though, which is to allow people to edit Microsoft Word and Publisher documents. That is where Dropbox has been a real help. I use it to
- Share files with co-workers, automatically keeping everyone's copies synchronized
- Work on files from different computers without having to do anything manually to keep them synchronized
- Keep online backups of projects I'm actively working on, so that the backup is always current.
- Download and install the free software (currently a 14 MB file). It creates a special My Dropbox folder on your computer.
- Register as a user with the service. You get a 2 GB online folder free, and can pay for more storage.
- "Once installed, any file you drop into your Dropbox folder will synchronize and be available on any other computer you've installed Dropbox on, as well as from the web. Also, any changes you make to files in your Dropbox will sync to your other computers, instantly."
- Dropbox does not transfer the entire file each time it is changed, but only sends the changed portions. This means that when I change one word in the 20 MB file, only a small amount of data has to be sent back and forth over the Internet, not 20 MB. That makes it useable over our low-bandwidth connection.
- I create an "AIDS is Real" folder inside my Dropbox folder and drag my 20 MB aids_is_real.doc file into it.
- If my collaborator does not already have Dropbox installed, I send her an invitation to install it.
- I mark the AIDS is Real folder as shared with my collaborator, for reading and updating.
- The Dropbox software automatically downloads aids_is_real.doc into my collaborator's computer.
- I open my copy of the document from my local Dropbox folder, make some changes, then save and close the file (changes are not synchronized until the file is closed).
- Dropbox software automatically saves my changes to the online copy and to my collaborator's local copy. When my collaborator opens her copy, it is always up to date (as of the last time she was connected to the Internet).
- Likewise, when my co-worker changes the file on her computer, those changes will be reflected in my local copy (almost) immediately.