Color-coding your inserted calendar data

Something our QA department has been doing for almost a year now has suddenly struck me as a really really good idea suitable for blogging.
Did you know it's possible to color-code your inserted calendar data?
What amazes me is how simple it is.
In the following example we've inserted several times (with a minimal data set) adding additional digits to our usual Category string:

All you need do on an individual basis is Manage the categories (seen here in OWA our client of choice on the Cloud).

You can also use Group Policy to propagate this for everyone if that helps you out. See Configure Categories in Outlook 2007.