Brakeman (http://brakemanscanner.org/) is an open source static analysis tool which provides painless vulnerability scans of Rails code from "rails new" through deployment. Running Brakeman as a part of continuous integration provides feedback during all stages of development and can alert developers immediately when a potential vulnerability is introduced. Bringing security testing as close to the developer as possible (even scanning as files are saved) means security problems are caught faster - and the sooner problems are found the cheaper they are to fix.