I used Rustoleum Hammered Black on mine. It held up for about 4 years, but is now pretty worn and needs to be redone. Pretty easy to do though... just need to take some time out and get it done!

I recommend disassembling the whole rack so you can get paint on all the metal... then put the feet and everything back on. You will have to get everything lined up again, but you'll be glad you didn't just tape off the plastic parts. Oh, I got down to bare aluminum on mine in places and the Rustoleum covered fine.

I might try putting a clear coat over it next time to see if that will keep it nice longer...