You'll need a medium-size adjustable pipe wrench to tighten and loosen pipes and other plumbing connections. You can purchase one at hardware stores and plumbing-supply houses.
A basin wrench is a specialized tool that allows you to reach tight spots under sinks and basins. The jaws of a basin wrench not only adjust to accommodate nuts of different sizes, but they also flip over to the opposite side so you can keep turning without removing the wrench.
A socket wrench set is useful for removing recessed packing nuts and for use on tub and shower fixtures as well as other do-it-yourself household repairs. For changing a toilet seat, you'll need a wrench, or perhaps a deep socket wrench. If you need to remove a toilet for replacement or repair, you may need a spud wrench. Older toilets frequently have a large pipe -- called a spud -- that connects the tank to the bowl. The spud is held to the bowl and tank by extra-large hexagonal slip nuts. A spud wrench is designed to remove these slip nuts. The adjustable type of spud wrench is far more versatile than the nonadjustable type, which has a fixed opening at each end.