You must have come across Twitter profile pics recently where people have added little overlays to show their support for a cause or their favorite brand. One way to do that is to edit your profile image in an image editing software. However, that can be time consuming.
An easier way is to accomplish that is by using Avartize. Avartize is a Twitter application that lets you add an overlay to your Twitter pic by simply choosing an overlay and then signing in to your Twitter account. You can choose from the hundreds of overlays already created, or create one of your own.
Using Avartize is also an effective solution if you want a group of people to display a certain overlay at a certain day for a cause. Avartize would make it easy because you will only have to create the overlay only once.