I have a suggestion that what if we have a option to select a file (especially, image) from the clipboard. Similar to what we have in Opera browser (sorry if mentioning other browser is disloyalty).
As we can copy an image directly to clipboard in FireFox. Suppose, in FireFox, we need to upload it to another website we have to download/save as and then upload.
Opera example:
This is how opera handles it, you can chose from clipboard which is very handy and I miss in FireFox.