For analog photo-graphy hobbyists, here's a novel utility that converts a compatible smartdevice into a handy light meter - "LightMeter" by David Quiles.
Compatible with handsets running on Android 3.2 or higher, the app works best with camera-phones that can save EXIF data - touting support for spot measuring, incident light metering and reflected light metering.
Though the app is not an alternative for single-function professional-grade light meters, its features are good enough to meet basic photography light-metering needs.