To my knowledge there is not an aftermarket chamber indicator but I haven't had a trouble with my 2 XDs. Jd's suggestions of painting it would ceratinly. I would caution you in painting it as the brightness of the newly painted indicator may get in the way of your aiming by blocking or overpowering the front sight. I know the indicator on my 45 sticks up much higher then on my 9. Just something to think about.
If the pain is lacking so is the discipline...
"the only 911 call I need is chambering a round" - Mr. Muller, MO car dealer