I dropped my crackberry from work, and it somehow landed on top of my evo (which was sitting on my table) and dinged the edge.... a day after, i was sitting down on break with my phone on my lap, and it fell when i stood up and left a nasty ding on the same corner.
i tried applying a VERY small dab of black sharpie on the dings.... it helped a bit but it still pretty obvious.
I suggest the touch-up paint idea, or just live with it... OR buy a new evo
and sell your old one on craigslist. you'll probably lose a bit of money in the process, but you'll have a new (unscratched) phone.