Drag text from a webpage so that it gets saved as a text file

If I drag an image from Firefox to say, my Desktop, the image gets
automatically saved, which is awesome.

Now, how about this : If I select some text from a page and drag it to
my Desktop, it gets saved as a text file automatically. However, if I
select and drag over an existing text file, the text gets appended to
the text file.

That would be like, super cool.
What do you think?

[this can also be done as an add-on]