I use Gmail, and although I love it in general, one thing that is a little tedious is that when you want to send someone an attachment, you can’t drag and drop the attachment onto your message like you can with most native email clients – instead you have to click “Attach a file,” then click “Browse,” and then browse to the file that you want to attach.
But dragdropupload is a slick little Firefox extension that addresses this problem. Once you install it, you can drag and drop any file from your computer on top of the words “Attach a file” in Gmail. Sweet! (You can also drag and drop onto any other website that does file upload, but Gmail is where I find it most useful.)