I recently had the requirement to flag customers with warning messages so the CSR would immediately notice that the customer needed special care (e.g. VIP customer, or mentally ill patients). The customer wanted some kind of color-coding in the form; however, they decided to not use any unsupported customizations. Instead, we used the form header to capture this information and use regular attributes to do so.
Today I saw a post from Matt Parks which gives us a great solution for the same problem. Unfortunatelly, it is still unsupported in CRM and might break in the future, but it is simple and can be extremely useful, see the screenshot here:
To see the article by Matt on how to do this, click here.