I have 3 normalised (0-100) raster maps. Is it possible to get a map which shows the standard deviation? I'd like to see the areas with smaller and higher std deviation.
You can use the GRASS GIS plugin to complete this task. First setup your views and map coundaries for your rasters in GRASS. Import your rasters into GRASS. You then want to use r.series function in GRASS to do this. It can take multiple layers, compute multiple kinds of statistics and render a result raster that visually represents those statistics.
Here is the manual on r.series
There does appear to be a problem with the plugin that keeps reporting invalid characters in filename for the input layers. But if you use the GRASS console to execute the function the results work.
Here's a general process