We have done several things here over the past couple of years...none of which specifically to save water, but as we are doing our home improvements and repairs, we do try to pick products that are more conservation friendly.
I got rid of our pool a couple years ago - it was an above ground that we inherited with the house. I am SOOO glad it's gone and that saved a bunch of water.
More recently, I replaced both toilets in the house with low flush. The newer ones are great and the ones in the house originally were from the early 80s and definately more than 2 gal a flush. I wanted to put new floors down, so just made sense to replace the toilets out while I had to take them up for the floor.
My washing machine went kaput and I replaced with a front loader. Average washing machine uses 40-60 gal PER LOAD. The one I got uses average of 12-16 gal per load.
I also replaced my shower heads which were 2.5 GPM restrictors with the kind that has the long hose on there. Again, not specifically to save water, but wanted the longer hose to make bathing kids and dogs and washing the tub easier. But, while I was at it, picked a model with very low flow, and since it has all the adjustable massage functions that makes up for the lower flow.
Our water bill has dropped by 1/3 since I made these changes (even not counting the pool which was a couple years ago)! My MIL lives with us and has her own washer/dryer. When she's ready for a new one I'm going to 'urge' her towards the front loaders too!
My kids also never flush the toilet.... of course that isn't in an attempt to conserve water, just a bad habit they have...!