Google added a new HTML5 feature into Gmail that has recently been included in Firefox and Google Chrome: "selecting files using drag & drop." If you use Firefox 3.6+ or Chrome 4+, you can now add attachments by dragging the files from your favorite file manager to Gmail. When you drag files, Gmail shows a drop zone to place the files. "We'll enable this for other browsers as soon as they support this feature. For now, you can drag and drop attachments in Chrome and Firefox only," mentions Google.