There's a report @ arstechnica.com that says some Chrome and Firefox extensions slurp up your browser history and some personal data and send it to Nacho Analytics where it can be purchased. The notable extensions include: Fairshare Unlock, a Chrome extension for accessing premium content for free. (A Firefox version of the extension, available here, collects the same browsing data.) SpeakIt!, a text-to-speech extension for Chrome. Hover Zoom, a Chrome extension for enlarging images. PanelMeasurement, a Chrome extension for finding market research surveys Super Zoom, another image extension for both Chrome and Firefox. Google and Mozilla removed Super Zoom from their add-ons stores in February or March, after Jadali reported its data collection behavior. Even after that removal, the extension continued to collect browsing behavior on the researcher’s lab computer weeks later. SaveFrom.net Helper a Firefox extension that promises to make Internet downloading easier. Jadali observed the data collection only in an extension version downloaded from the developer. He did not observe the behavior in the version that was previously available from Mozilla’s add-ons store. Branded Surveys, which offers chances to receive cash and other prizes in return for completing online surveys. Panel Community Surveys, another app that offers rewards for answering online surveys Suggest you read the whole article using the link at the top. Personally, I run all browsers without any extensions for performance and security reasons.