Image To Data is a very helpful app created with web designers / developers in mind. With a simple and fast gesture you can turn an image for a web site in a base64 data url. Simply drag a file on the dock icon or the blue window of the app and you'll have it copied in the Clipboard!
√ Simple, intuitive and fast to use
√ Always available on the desktop when open
√ Drag an image on it and let it be converted and copied to the Clipboard
√ BONUS: convert not only images but other files as well!