Persinger's "God Helmet" is pretty interesting... all it does is uses magnetic stimulation, known as rTMS rotating around the head at a certain frequency and can cause intense euphoria and feelings of being one with God or intense religious experiences. However, this kind of magnetic technology has to be localized and isolated, therefore it is not like there could be a tower making a whole town hallucinate, at least not using this technology.
Also no, SSRI's don't "change" your brain chemistry. Once it is out of your system (~72 hours) the reuptake inhibitory mechanism is no longer effective and that is exactly what a SSRI does, hence the name Selective Serotonin Reuptake Inhibitor. There is no doubt that it is doled out to people who don't need it but when it is used in the correct applications (chronic clinical depression with a chemical origin, as in the patient does not have anything initiating the depression and it is long lasting/insoluble) it can be an effective drug with minimal side effects. It isn't a narcotic or addictive like Xanax and other benzodiazepines and can be really helpful for those who struggle with chronically low serotonin levels. Giving it to kids, people who are sad because of a breakup or anything like that is just horrible and people who do such things should be stripped of their licenses.