Ok, I will admit it, I have rust stains in my tub, toilets and sinks.  I know it's not my fault but I still want them to sparkle like the day they were installed.  I also want to use only household cleaners that are healthy for my family and the environment.  So you can imagine my joy the day that I discovered that grapefruit juice works great for removing rust stains in all these areas.  Just purchase 100% grapefruit juice (I buy the generic kind, no need for fancy in the toilet bowl) and pour it directly onto the stained area.  Scrub if needed and you are good to go!