Dropbox is a nifty little service that I like to compare to a virtual USB key. You can sign up for a free account that gives you 2GB of storage up front (with an opportunity to "earn" more space), and if that's not enough, they have paid accounts that you can buy to have more storage. You set up a folder on your computer and anything you put into it, syncs with the Dropbox service so it's accessible from any computer (as long as you log in). You can choose to share files you place on Dropbox (so if your sister wants full resolution pics of her kids that you put on Facebook, you can put them in Dropbox for her to grab), or you can keep them to yourself.
You can set up multiple computers to sync with Dropbox and then anything in the folder is automatically shared with all computers. For example, my husband and I have our iPhoto library stored in Dropbox (we break off a new library every 6 months). This way, whenever he or I sync our photos from our cameras/iPhones to our computer's iPhoto library, they automatically are available to both of us. Which is good, because I'm the one that does the photo printing/uploading to Facebook, while my husband is often one to take pics with his iPhone.
You can also access your Dropbox files from work or other locations, so this can come in handy if you need to access personal data throughout the day, but perhaps you don't have it with you on a USB key. It also means you don't have multiple versions of a document or file kicking around - you are always accessing the latest version on Dropbox.
As an added bonus, since Dropbox is storing your files, if your computer decides to stop working for whatever reason, your files are safe and can be accessed from other devices or you can just pull them back onto your computer once it is repaired/replaces.
The free account comes with 2GB up front, and you can do things such as referring others for space credits. Speaking of which, if you are intrigued, you can certainly use my referral link to sign up: http://db.tt/zuBjhfY.
Dropbox is a pretty simple way to have instant access to files you need, without having to remember to carry them with you on a USB key. It is also a nice way to back up things that you wouldn't want to lose if your computer suddenly died, such as your resume or perhaps a selection of your wedding photos. And since it's free, it's a no brainer if you've ever wished for a little more tech convenience in your day.
Check out more at http://www.dropbox.com or if you don't mind, use my referral link: http://db.tt/zuBjhfY