The medicine cabinet also benefited awhile ago from re-purposed metal boxes which used to hold small miscellaneous office supplies on a big desk from our Mass. house, but no longer fit on the small desk in our apartment. A quick tidy-up here was all that was needed (and a few expired products that were tossed along the way!)
The under-the-sink-cabinet benefited from two upgrades - I borrowed a Target storage box from a kitchen cabinet (which had been holding a measly one spare lightbulb) and filled it with "spare" or not-used-as-often products, and added a command hook to the inside wall to hang up my hair dryer. Honestly, the command hook, simple as it was to add, has made a world of difference - no more pushing around cleaning chemicals to grab it at the back of the cabinet!
I included the medicine cabinet from the kitchen too and straightened that up a bit as well - now there's good storage space for first aid and medicine (as well as batteries, tools, wax tarts, and that one spare lightbulb!)
So this challenge, quick and easy as it was, actually made the list, and I was happy with the results (unlike the deep-clean-your-kitchen-appliances challenge which for some reason I have not yet found the inspiration to get around to...)