When browsing the JSTOR webpage, the JSTORpdf bookmarklet will directly access the PDF version of an article. It will go straight to the PDF within the current browser tab, without the multi-click licensing hurdle and without popping it into a new window. This makes it possible to be more organized about literature searches, not having PDFs in open windows cluttering your workspace.
JSTORpdf works in Chrome/Firefox by very simple means, though JSTOR occasionally makes changes to their site that break the bookmarklet. I try to update the code when I notice it is broken. If you notice that it is currently broken, feel free to drop me a line at the email above and I'll try to fix it.
Last update: 1/23/15