Urine typically is a shade of yellow. There are a few disorders which change the color of urine in a dramatic way. To be specific one should see their doctor. Generally when urine gets brown or Coke colored it suggests a liver or bile duct problem. Red urine can be blood or can look red from certain medicines.
Black urine is classic for a genetic defect.
The shades of yellow of urine are usually related to the concentrated of urine. If you swallow a vitamin B2 supplement, and the amount is more than your body needs, the vitamin is excreted in the urine. But there is nothing wrong with you when this happens - it is just your body getting rid of extra vitamin B2. Some health authorities use this as an example that taking large doses of vitamins only makes expensive urine. However, nutritionists who advocate large vitamin supplementation counter by saying that it is only when the excess amounts of vitamins spill over into the urine that you know for sure that your body is getting the maximum amount of the vitamins.