Found is a system utility that lets you add your Dropbox, Google Drive, Gmail, SkyDrive, and Evernote accounts and search for any file stored in them. You can also add local folders or network locations to Found. When you want to carry out a search, you can either do so by clicking on the menubar icon or by pressing the control key twice. This will open a panel that slides in from the right. You can start typing right away, and Found will present search results as you type. The results will be grouped by source. In other words, the results from your Gmail account will be separated from those found on your local folders. This makes it really easy to search for anything.
Found uses Quick Look to help you preview your files. It can display images, videos, text documents, and anything that the Quick Look feature can open on your Mac. The results can be dragged to any window, which allows you to copy files from Found to other folders quite easily.
Setting up Found was easier than I expected. The first time that you run it, the app will ask you what folders you want to add and what cloud services you would like it to search. If you want to add more later, you can do so from the Preferences window. There is even an audio tutorial that explains the basics.