Arxiv equivalent for medical research article I'm looking for a suggestion, for a medical journal counter part to the arxiv. A minimal frill, open access online repository 
to time stamp articles with some visibility.
To elaborate on the answer by ddiez: bioRxiv has been deliberately designed to fill the same sort of role for life sciences that arXiv does for physics, math, and computer science.  A key reason for this is the growing recognition amongst some practitioners in these fields that scientific communication is being inhibited by the long time to publication and pre-publication secrecy that is typical in life science fields---it is not uncommon to be hearing privately about work for years before one is able to read the details or cite it.  Overall, this is a very good thing: it improves communication, it reduces the chance of being "scooped," and it reduces the "all-or-nothing" pressure associated with targeting super-high-impact journals.

That said, bioRxiv is still fairly new, and the conventions for its relationship with journals are still evolving.  Some journals are very supportive and encourage authors to deposit in bioRxiv.  Others still tightly embrace the prior publication culture and consider deposit in a preprint repository a prior publication that precludes submission.  Check carefully what the policy of the journals that you are targeting with before you make a decision about whether to deposit.