Dropbox synchronizes files across your/your team’s computers. It’s much better than uploading or email, because it’s automatic, integrated into Windows, and fits into the way you already work. There’s also a web interface, and the files are securely backed up to Amazon S3. Dropbox is kind of like taking the best elements of subversion, trac and rsync and making them “just work” for the average individual or team. Hackers have access to these tools, but normal people don’t.