A step stool to reach the upper shelves of my 40" uppers, of course! And a few cleaners.

All that stuff seems to take up a lot of room under our sink! ;-)

Dishwasher tabs, dish detergent/liquid handsoap refill, extra sponges, scrub brushes, spray cleaners of a few sorts, including the gallon bottles of concentrates that get diluted in the spray bottles, cleanser, large garbage bags, and 2 fire extinguishers. (I know there has been discussion about that being a bad place to keep them...)

I like that the garbage is no longer mixed with all those things, and nothing else has to be either.

Ditto everything rhome410 wrote.

I have two sinks...a large one in the scullery area, with two pull out bins under it. It stores, a variety of cleaning stuff, a dish drying mat, stool to reach upper cabinets, dustpan and brush, jet dry and dishwasher tablets, Never-M-T with dishwashing liquid, tool for unjamming disposal, extra cutlery bins for dishwasher and perhaps a few other things.

Smaller front sink stores, more cleaning suppplies specific to that part of the kitchen (stainless polish, for example), fire extinquisher, Never-M-T with dishwasher liquid, a plastic tub in which I throw dirty dishrags and towels until they get transferred to the laundry. When I get someone in to finish up the kitchen, the cleaning supplies will move and a can crusher will be mounted here. Took me a while to find one that mounted horizontally so it would fit, but eventually I did.

hope this helps.

I have a 36" sink base. The right side is the reverse osmosis system with a tank, an instant hot and various cleaners and some Clapham's for the soapstone and butcher block. The left side is a double bin pullout trash and a four outlet block to power everything. I'm still debating whether or not to add the Blum servo motor for the trash. Sadly, I don't have any room for my disposal, which I had wanted to recycle from the old kitchen. It's a compromise I can live with. I really didn't want to waste a perfectly good cabinet for trash and I certainly wasn't going to waste any space under my sink.

My trash cabinet has recycling in it. One bin for redemption items and the other for general pick up. When it's not being kicked around the kitchen, the garbage pail (with lid) lives under the sink. I like having it where I want it, and being able to hide it when it's in the way. That way I also don't have to have nasty garbage inside my cabinets.

I have a roll out tray shelf on the bottom of my big sink cabinet. It makes it so easy if the plumbing needs attending to. It can just be lifted out. Makes it easy to get to the stuff at the back too. Besides the sometime trash, it holds a pop-up bin for recycling at parties, extra sponges, sink accessories, rubber gloves, etc.

Under my prep sink, a very small cabinet, is the fire extinguisher.

under my sink I have 3 drawers.

It looks like two deep drawers because the drawer fronts are about 15"h.

A shallow internal drawer is inside the one and only deep drawer at the bottom of the cabinet.

The highest drawer looks deep. It is mostly occupied by the sink. So it is really mostly a shallow drawer. One one side I have a few inches of deep, because the sink doesn't span across the entire cabinet.

Besides the disposal unit, I keep a small basin (as I have large single bowl), stainless steel wipes and cleaner, granite cleaner, dishwasher gels, ceramic top cleaner, and drying mats, new sponges and a jar for old cooking oil

I have tray holders in part of the prep sink cab and that's where big cutting boards live, oil for the countertops, garbage bags and extra large pot lids - its near the pots and range. I thought of using some space for built in veg storage, but it turned out to be too warm.

Under the other sink, we have stone foundation walls, so the rough in is pretty far forward limiting the amount to be gained by drawers. So it has the same collection of stuff as rhome's - including the fire extinguisher.

I had never heard of anyone keeping a garbage can under the sink - so that choice might be regional or socio-economic or decorative. :)

One reminder is that a lot of the sinks are deeper and undermounted - a 10" deep sink will extend 4-6 more inches into the cabinet pushing stuff like garbage disposals and dw hoses down quite a bit.

We have a drawer in the trash/recycle cabinet that holds the trash bags.

Under the sink is storage for cleaning products and the compost bucket. They sit on two trays. The bucket's only used for overfill in the event I can't take the counter top bowl to the compost bin.

I grew up with it under the sink, too. That's the 1st place I still look.

I have an apron sink now and my garbage is in the left, 24" base cabinet.
However, I find those stupid little doors under an apron sink inefficient and a true PIA. I'm not getting down on my knees anymore to find something I might need once in awhile. I'd be more likely not to do the task for which I needed that something. And to tell you how lazy I can be? I teach yoga. I spend hours and hours on my knees or getting up and down therefrom.

I have made a drawer that is cut lower in the back to fit under the garbage disposer & plumbing. That means on either side of it I can store taller cleaning stuff, sponges, etc. No getting up and down and no wasted cahb-net space.

Do you keep your garbage under the sink in the bathrooms, too? I do.

Never had a trash can under the sink...not even growing up. To me, it seems too unsanitary to have a trash can there. (A covered trash can would make it less distasteful to me. But I have seen far too many uncovered and overflowing trash cans under other peoples sinks for me to feel comfortable w/an under-sink trash can.)

Cleanup sink...Like most others, I have cleaning supplies plus trash cans. The garbage disposal takes up quite a bit of space, so there is not as much space under the sink as you would think.

Prep sink...Cutting boards in a "tray divider" so they can utilize the nether regions of a corner sink base, pizza stones + my only cast iron pan in another tray divider on the other side of the cabinet (also utilizing the unreachable back of the corner cabinet), cans I've saved for draining fat, hand lotion, and granite cleaner.

Under my cleanup sink looks very similar to Natal's except I have a garbage disposal instead of a compost bucket.

Here's a pic of under my prep sink:

This is under my main sink:

With pullouts extended:

1) Paper bag for the paper recycling.
2) Rubbermaid dishwashing bin holding colanders of all sizes (so they are handy at the sink, point of use).
3) Rubber gloves for dishwashing.
4) Wooden cutting board that fits over one half of the sink when we need an extra prep station.

Cleaning materials are all on an upper pantry shelf for kid safety.

Thanks for the photos and feedback, everyone! All great ideas to add to my list.

Someone recently posted pix with a thin tension mount curtain rod across the sink interior that they hook their spray bottles on and they are easy to access quickly. I thought it was pure genius, but have not done it yet.