Dropbox, which ranks well on maximumpc.com's list of "32 Totally Essential Apps," is actually a really nice service. Here's the idea:
Dropbox integrates with your computer shell to provide you a "fake" folder on your computer. It is "fake" because the folder is not actually on your computer---it seamlessly synchronizes what you put into the folder with what's being stored elsewhere (in your "dropbox"), and lets you grab it from your dropbox as well. The whole thing is intuitive---it looks and acts just like any other folder on your system!
There are several account types available, but I'll be sticking with the 2GB that comes with the free account. Also, you can earn up to 3GB more through referrals.
Aside from making a simple, free 2-5GB extension to your hard drive space, Dropbox also comes with some nice other features. First, you can access your files in the dropbox from anywhere. Just login to the web client (or download the local client) and you're set!
As well, you have a "public" folder that can be accessed by anyone. When you put files in there, you can right-click and get a public access link, and voila---free hosting! For an example (that I'll eventually delete), this file is in my public folder (it comes in there by default): http://files.getdropbox.com/u/1617350/Top%20Secret.txt
The other feature I'll mention is of particular interest to BYOND developers. You see, software developers oftentimes work in flocks. And a flock of developers needs some way of privately sharing the developments among one another. With Dropbox, you can create "shared" folders that are available to a list of users you choose. That means if you were putting your game's project files in the Dropbox, you could share that folder with the rest of your team, and you'd all have access to the same folder of files. Imagine the possibilities!
It's available on Mac, Windows, and Linux, so I suggest you check it out now! Oh, and if you're going to register, use my referral link---we both get the extra space! :]