I frequently need to deal with the contrast and brightness of raster layers in QGIS and I miss the tools in ArcGIS for this task. Should there be a plugin already developed for QGIS? If there is, where can one find it? Regards.
To my knowledge, there's no plugin as such (although one would be useful). But you can achieve the same effects albeit with a bit more effort, by changing the range of RGB values for that raster layer.
As Giovanni says, QGIS is rapidly becoming a mature and popular project, and your support is always welcome. Funding a feature-request is the best way of getting a plug-in to do what you want.