I love Dropbox (www.dropbox.com). Like most people these days, I work on multiple devices. Losing flash drives is a common problem for me. I use Dropbox as my solution for this issue.
To use Dropbox you navigate to their site, create an account, and download the application onto your computer. Apps are also available through the Apple Store. Once installed on your computer a folder named "Dropbox" will appear in your Computer menu. Save or drag and drop files to the Dropbox folder to save them in the cloud. Your files are accessible on any device where you have the app, as well as online. The documents will sync across all devices so you always have the most recent version of the document or project.
I have the App on my work computer, home computer, iPhone, and iPad. Love it!!!