A little discussion of many of the issues: http://alexholcombe.wordpress.com/2011/10/24/opening-access-with-peer-reviewing-pledges/
What is the relationship of this site to researchwithoutwalls.org ?
This site was started in late September, independently and at approximately the same time as ResearchWithoutWalls. Perhaps it is an idea whose time has come!
ResearchWithoutWalls was created by members of the computer security community who were focusing on computer security conference proceedings and journals. They are using a stronger (but customizable) pledge of reviewing exclusively for open access conferences and journals. This appears to be appropriate in their context because making the main computer security outlets all open access is one that may be achievable nearly immediately. How feasible that is for other fields varies enormously, and depends on funding sources and tradition.
Each individual person who makes a pledge should make a difference, but as individual fields reach a tipping point, of course the influence of each pledger is likely increased. In some areas, there are no open access journals, and the effect of the pledge here will be to gradually increase the number of openly available articles, which should reduce the ability of publishers to charge exorbitant prices, as it will be more practical for current subscribers to do without a subscription.