Various applications in OS X support changing the color of elements such as text, annotations, and other markups or drawn objects. For instance, in Pages or TextEdit you can highlight a section of text and then set the color of that text using the color box in the toolbar.
This option is not uncommon, but while some programs offer a small selection of colors to choose from or have their own color settings implementations, those that use Apple's core technologies may give you access to the OS X color panel. This panel provides a variety of options for finding the exact colors you wish to use, including a color wheel, RGB sliders, preselected color palettes, and even common crayon colors or other swatches.
Another notable option for the color panel is the spyglass tool, which when clicked will allow you to sample a color from the screen and reproduce it in the color panel, making it convenient to match and adjust colors between projects and objects you are working with.
When you have a color that you would like to use, you can drag it from the preview section (at the top of the panel window next to the spyglass) to a tile in the favorites drawer at the bottom of the window. When saved, this color will now be available in the panel from any application that supports it. You can also drag the individual colors from the presets to the favorites drawer, without needing to use the preview field.
When saving favorite colors it may be tempting to randomly use available tiles in the favorites drawer; however, this can become a cumbersome clutter as the number of favorites grow. To help tackle this, you can expand the drawer by dragging the dot at the bottom of the palette up or down, and also by expanding the palette's size horizontally (the maximum number of tiles is 300 in a 30x10 grid). With a larger favorites grid, you can then drag your favorite colors around and arrange them in a more useful manner.
Besides potential organization problems, one issue with the favorites drawer is the ability to delete favorites. Apple does not provide an intuitive way to do this. There is no contextual menu for the favorites drawer, so right-clicking the colors shows no hidden options, and there is no way to select and delete a color since clicking or double-clicking will only load the presets that represent that color.
While not the most intuitive approach, if you want to clean up the favorites drawer a bit, you can delete individual tiles by simply dragging a pure white color to the tile that you wish to delete. This can be done either by dragging a white color from the panel's preview field or by dragging a neighboring white favorite tile to the tile you wish to delete.
In some instances you may have an entire favorited drawer filled with random colors that you might wish to completely clear, and managing them one tile at a time can be cumbersome. In these cases, instead of dragging white colors to each tile you can delete the settings file for the color presets from your user library. To do this, go to the user library (in OS X Lion you can get to the library by holding the Option button and choosing Library from the Go menu). Then navigate to the Colors folder and remove the file called "NSColorPanelSwatches.plist," followed by closing and reloading the color panel.