Open Access journals are more discoverable by scholars and the public than their non-OA counterparts. This increases the likelihood that others will find your material thus aiding in the wider dissemination of the work and the potential impact of the article. It is estimated that there is an increase in article citation between 17% and 250% with downloads of Open Access articles double that of their non-OA counterparts. (“The Antaeus column: does the “open access” advantage exist? A librarian's perspective”).
Who in my field is choosing to publish their work as open access?
List of Predatory Publishers - updated yearly. Become familiar with the world of predatory open access, which depends on spammish solicitation to convince researchers to contribute an article processing fee in exchange for ....unedited dumping into their "journal". Sometimes the incentive is that many quality peer review journals charge $1300-$3000 for an APC, while these predators charge $300-$1000, seeming like a bargain.
Some approaches to answering the key question for assessing the quality of any academic journal by Heather Morrison, March 6, 2011
The smart scholar’s publication-venue heuristics; or, how to use open access to advance your career - Oct 22 2010 Published by Dorothea Salo under Open Access
The effect of open access and downloads ('hits') on citation impact: a bibliography of studies - The Open Citation Project
2010 Self-Selected or Mandated, Open Access Increases Citation Impact for Higher Quality Research. PLoS ONE 5(10): e13636. doi:10.1371/journal.pone.0013636
How to assess new open access journals
Journals that allow deposit of the publisher pdf in IRs.