A little side project is now available to play with at liquidchapter.com/search.html
We were tired of being asked to pay for old journal articles so we knocked up a search that only indexes journals which make their articles available for free without payed subscriptions (NB BMJ requires once off free registration)
You can also filter for only radiology journals or only Radiopaedia.org
Have a play and let me know what you think. If there are journals missing (I am sure there are) let me know and we will add them.