Enlarged Debuff Icons
Make debuffs / DOTs that are yours larger than others so you can distinguish between other classes. That way you can quickly determine when your dots have fallen off.

or

DOT Timer
Give us DOT timers (meter style) can is clearly visible to help with our damage dealing.

Of the two options I like enlarged debuff icons, since it is minimal but a vast improvement over the current system which is keeping track of your own icons.