We have seen the success of green open access with direct author self deposit of journal papers to repositories increasing all the time. Ease of access and funder mandates have sharply increased both deposit and readership and subsequent impact. In our own document repository epublications@rcsi 900 papers and dissertations by RCSI authors have been downloaded over 293,000 times.
There is a corresponding increase in publication in gold open access journals, the access model where authors pre-pay publication fees but readers view without charge. There has been a measurable increase in citation impact from gold open access publishing. The BioMedNet Central suite of journals is a well known example of gold publishing in medicine and over 300 papers by RCSI authors are freely available in BioMedNet BMC titles.
There are many other gold open access (OA) journals in clinical medicine, molecular biology, pharmacology and psychiatry. You can use the DOAJ directory, Directory of Open Access Journals to find all OA journals in a category. The growth of gold OA, plus a listing of the highest impact OA titles, is presented in a recent article, itself open access. On the impact of Gold Open Access journals Gumpenberger, C. et al 2013 Scientometrics 96 (1), pp. 221-238