When we were first married, I used to insist my husband and I purchase a toilet brush with a disposable head. I've come a long way since then. We now use normal toilet brushes.
We used to use paper towels for everything. However, once our little guy started eating, he was getting really messy. We used more paper towels than ever because the dishcloth from the kitchen sink seemed way too yucky to wipe his precious little face with! Then I decided to cut up the abundance of 'free t-shirts' my husband had hoarded for ages. He willingly gave them up to this worthy cause. Now we launder the t-shirt rags several times per week instead of using rolls of paper towels.
The next disposable item I am phasing out are Swiffer cloths. I can't believe I haven't considered cutting my own Swiffer-sized cloths out of fleece before now. They will pick up dust just as well and can be laundered with the other rags I use for cleaning. Not only will this be a one-time cost instead of every month or so, I won't have to store the large boxes of cloths. I had been buying the store brand instead of Swiffer brand, anyway, but so much money can be saved.