Give all your tips and tricks to cure the dark bags under the eyes. If you have tried something and it doesn't work, tell us! I've been trying to put ice under my eyes and so far, I haven't really seen a difference.
Ice won't make a difference because there's no swelling on the surface of the skin, it's the blood vessels so ice will help eventually but I'd try using something other than ice. I'd try relaxing and putting cucumber on your eyes and relaxing with a face mask packed with vitamins A, C and zinc.
You can buy the under eye roll on's which have Vitamin K in them but I'm not sure if they work or not. Another method that I personally use is putting cold tea bags on my eyes, dip tea bags in cold watter then put them in the fridge for a couple of hours then rest them on your eyes.
Eat well, loads of fruits and vegetables especially things like cabbage, spinach, and other leafy green vegetables, maybe you could take a daily vitamin supplement on the days when you don't take in enough vitamins. Drink lots of water to improve circulation too.
If you smoke, stop - that will improve circulation. Make time to relax more, stress can cause dark under eye marks, make sure you sleep for an adequate amount of time and take time to wind down at the end of everyday. Eat less salt as this can result in puffiness under the eyes. Too much salt can impair your circulation and cause the blood vessels under the skin to appear darker.
If none of these work, buy one of those creams but do all these natural things before you go out and spend a small fortune! Good luck.
I think it's a sign that you are not blinking enough, and the area below the eyes is not hydrated enough. Try not using your computer as much for a couple of days (where possible) and maybe using some sort of moisturiser (I can't recommend one) that you can keep away from your tear-ducts.