Would love to be able to mark different tasks as different colors for various purposes.
Have you thought about using tags or custom fields to accomplish this? For example, a lot of people will use a tagging system such as ‘On hold’ in red, ‘In progress’ in amber and ‘Complete’ in green.
If you use custom fields you can also set up a drop-down with different options in different colours, and people can change them as they progress.
With either option, you can then create advanced searches for tasks associated with certain tags or fields, so it makes it much easier to track and report.
@Alexis wrote a great post on this elsewhere, which might help you decide which to use: