I found a particularly good blog about how to color your Calendar lists similar to the way Outlook’s are formatted using the Content Editor Web Part and some nifty Javascript HERE.  This particularly valuable post comes to you from PlanetWilson SharePoint Blog, a particularly good source of information for MOSS solution.  There is a packaged solution file (which I have yet to try because I hear it lacks the incoming e-mail feature of WSS 3.0 calendars) and a nice walkthrough demonstrating how to setup your ”coloured” calendars.  I used it and it works great, here is a image of what I was able to create in about 30 minutes.