I had exactly the same problem a few months back and ultimately just wrote a tool to do it for me. When I saw this and found someone else had the same itch I cleaned it up so that someone other than me could actually get it running, and finished off my to-do list. The code is up now: https://github.com/mwh/dragon
To get it, run
git clone https://github.com/mwh/dragon.git
cd dragon
make
That will give you a standalone dragon
executable - you can move it wherever you want. make install
will put it in $HOME/.local/bin
.
Either way, you can then:
dragon *.jpg
to get a simple window with draggable buttons for each of those files:

You can drag any of those into a browser, a file manager, an editor, or anywhere else that speaks the standard drag-and-drop protocol.
If you want to go the other way, and drag things in to it, use --target
— they'll be printed to standard output, or available to drag out again with if you use --keep
as well.
To build you'll need a C compiler and the GTK+ 3 development headers - if you're on Arch you'll get those just by installing GTK+, but on other distributions you may have to apt-get install build-essentials libgtk3-dev
or yum install gtk3-devel
or similar first. Other than that it's entirely self-contained, with no constituent libraries or anything, and you can just put the executable where you want.
My use case is mostly one-off drags of only a few files (usually just one), without particularly caring how they show up, so if that doesn't line up with what you want then Dragbox (which I didn't see until recently) might still be better for you. Just yesterday I added the support for using it as a drag target as well, so that part hasn't had much use on my end. Other than that, though, I've been using this successfully for a while now. There are other modes and options described in the readme file.