Pavel, Not an empirical examination of efficacy per se, but some analysis of the old style of internet petitions in this old working paper of mine: "Please take a few minutes... : Using 'Pointless' Internet Petitions to Characterize the Shape of Acquaintance Networks" (http://djjr-courses.wdfiles.com/local--files/djjr-cv%3Aresearch/RYAN-petitio...) or 2007 CASBS Presentation (http://djjr-courses.wikidot.com/local--files/djjr-cv:research/CASBS-Petition...) Sciences Dan ---- Dan Ryan I work at Mills College o 5000 MacArthur Blvd o Oakland, CA 94613 o 510-430-3242 I write at http://djjr.net/papers/index.html I blog at  http://soc-of-info.blogspot.com/ I innovate at http://www.innovationexchange.com