FlatPanelsDK, a Danish monitor information site, has a set of free tools available on their site. Available both as portable downloads and web based tools you'll have your monitor tweaked in no time flat.
The online version of the test can run in full screen mode up to 1280x1024 resolution, for higher resolutions you should download the stand alone executable which can maximize to the full size of your monitor. The test allows you to examine the colour ranges, gradients, trailing, and homogeneity of your monitor. Additionally there is a pixelmapping and text contrast tool. One thing to keep in mind to avoid a moment of enormous frustration: the tool bar auto-hides right from the start and the only way to coax it out is to put the mouse right up at the top of the test window, there are no keyboard shortcuts or indication that you need to hunt for a menu.
Complimenting the monitor calibration tool is an input lag test. Essentially a giant timer, you set your monitors in clone mode so every monitor is displaying the same thing. Start the timer and take a photo of your monitor spread— remember to turn your flash off— and then compare the numbers on each monitor. The difference in the values is the input lag between the displays. Both the screen test and the input lag test are available online in HTML or Flash and as a stand alone executable. For other screen calibration tools, check out Calibrize and Screen Check.