Dropbox is quickly becoming a "must have" online storage service. In a few minutes, you can set up a Dropbox account and start synchronizing files among multiple computers and mobile devices. Offering a free 2GB of storage, Dropbox is an excellent alternative to USB thumbdrives or burnable CDs.

If you are interested in using Dropbox, the first thing to do is to watch their introductory video so that you get a sense of how the service works. Then download the software on your computer(s) and iPhone or iPod touch.

Once the Dropbox software is installed, a special folder will be created on your computer. Anything placed in this folder automatically gets synchronized with your Dropbox space and subsequently, to your other devices. Your Dropbox space can also be accessed via your Web browser, which includes a number of nice features including a simple gallery view for viewing photos and images.

Folders in your drop box account can be shared with other Dropbox users. This means that if new files are added or if existing files are modified, the changes will appear on your desktop, website, and portable device. There is also a "public" folder in which you can deliver files to anyone via direct URLs.

The system also features version control, which allows you to roll-back any document to a previous version. So if a file becomes corrupted or erroneously modified, it's like having a super "undo" button.

Dropbox offers a number of paid plans as well. So, if you need more than the free 2GB, you can opt for 10GB at $5/month and for $10/month you can 50GB.