In the minecraft servers I visit, I often find myself lurking around using Invisibility. However, I also often blow my cover through forgetting to renew said Invisibility.
This mod is a lightweight client-side remedy: it plays a sound (tick sound, configurable) every second for the last ten seconds of the effect. (also configurable)

contributing

have a feature you want to see, or a bug to report? head to the issues tracker! pull requests are welcome, too.