gcolor2 is described as 'basic colourpicker utility that allows you to select any colour on your screen, and, well, grab it's colour' and is an app in the Photos & Graphics category. There are more than 50 alternatives to gcolor2 for a variety of platforms, including Windows, Mac, Linux, the Web and iPhone. The best alternative is PicPick. It's not free, so if you're looking for a free alternative, you could try Just Color Picker or gpick. Other great apps like gcolor2 are Sip (Paid), Instant Eyedropper (Free, Open Source), Colora (Free, Open Source) and Colorpicker (Free, Open Source).