The RePEc team regularly gets requests to from authors to add this or that item to the database, or enquiries from editors why RePEc is discriminating against their journal by not listing it. It is therefore useful to discuss again how RePEc gathers all its bibliographic data, and thus what various users can do to enhance the listings.
RePEc does not have any data entry staff, one because RePEc has a budget of zero, two because the data entry is done by the respective publishers. The same rules apply to all, whether it is a large commercial publisher with many journals or a small research center with a working paper series: they have to open a local metadata archive with bibliographic information formatted in a way that RePEc services can automatically gather and analyze on a regular basis (usually every night). So far, over 1400 archives have followed the detailed instructions necessary for participation. Authors with institutions that fail to participate in RePEc can still get their work listed, by uploading it with MPRA. They need copyright clearance for this, which is granted by most publishers, according to the list compiled by SHERPA/RoMEO.
Author profiles are also maintained by the authors themselves, by registering at the RePEc Author Service. The citation analysis (CitEc project) also depends on the collaboration of publishers, either by allowing the free download of the full texts or by providing the metadata about references separately.
The extremely decentralized nature of RePEc is what allows to reduce central costs to almost nothing and thus keep RePEc free for all: publishers, authors, and readers. The collected data can then be offered by the various RePEc services, and those bear the (small) cost of massaging the RePEc data to make it useful for everyone.
The RePEc Blog 
Hi Christian, Open Access moderated Multicultural Crowd Sourcing avant la lettre! The second1000,000 document links will be added before 2020. Very good summary!
Best, Marius Ooms
Well, what to do when some journals (like Journal of Comparative Economics) do not have staff to report the new publications to RePEc? For instance, even the November 2011 issue of the Journal of Comparative Economics is still not recorded in RePEC!!!? On the other hand, there is no way how the authors can report such publications themselves. Thus, the record is not updated and thus not accurate…Regards, Kreso
Well, for journals the priniciple is that only the publisher, or an agent of the publisher, can input the data. This preserves, for example, the unicity of the record, and this also prevents any abuse. For preprints, however, there is more flexibility, even authors can submit their works through MPRA (and Elsevier does allow deposits there).
Yes, I agree with you but I am only pointing to the fact that when journal fails to do the reporting there is no way how to overcome this failure. Regards, Kresimir