Dead Pixel Tester was written to help me check my own screens (Couldn't find one that worked across multiple desktops so had to write my own!) by cycling through the three primary colours used (red,green,blue) and all on (white) and all off (black). Simply select a colour then closely inspect your monitor in each of the primary colours checking for pixels that are not operating as expected. Stuck pixels (always on) are easier to noticed then pixels that are not on due to their size (normally under .5mm).