#1--nasty, nasty buildup from the dishwasher on my glass drinking glasses. so here in utah they pulled sulfates out of the dishwasher soap...and my glasses have been cloudy and gross ever since. they were getting so bad, our finger prints were showing up in the buildup. GROSS. seriously.
long story short, i did some online research and found that vinegar was the answer. so i filled my sink (just enough to cover my glasses laying down) with hot water and some vinegar, soaked them over night...and wa-lah! sparkly clean!
there are a few small spots that could have easily been removed if i had been ambitious enough to scrub them, but i think i'll just soak them again when they start to cloud up again. (they also do say that a cap-full of vinegar in your dishwasher (after it's started to fill) will help prevent the buildup.)
#2--terrible hard-water stains on my glass shower doors. again...vinegar to the rescue, plus a few other ingredients. the online research results recommended lemon juice (applied with a sponge) for the most of it, and then a paste of vinegar and baking soda for the tough spots (but my whole door qualified as a tough spot if you ask me). then you spray with a mix of water and vinegar. then squeegee or finish with window cleaner.
this wasn't quite as dramatic as a result, but it still worked. i'm planning on doing a second round and hopefully it will all come off.
ah the power of vinegar...