In the bathroom to encourage hand washing I bought a step stool so they could reach the faucet easier. Ours is a The First Years Sit & Store Parent Bathing Seat and Stepstool. This sturdy stool with no slip feet also functions as additional storage in our small bathroom. I have it full of wash cloths for the kids. As the shorter step stool it can hold up to 300 pounds which is more then enough to hold both kids or give me a lift to change the shower curtain. If you turn the lid it is a few inches higher and a nice seat for supervising and helping baths.
Once the kids are high enough to reach the sink the mirror is still out of their reach. I picked up a mirror and foam sticky backs at the local dollar store. I installed it right behind the sink below the existing mirror. It is a the perfect height for the kids to see if they got all of the ice cream or cheese off of their faces or watch themselves brush their teeth.