Toilet rolls stacked on the floor of linen cupboard around the hot water cylinder (as per normal, just higher and deeper stacked).
Cleaning materials tidied up and tetrissed in the 2 shelves to the side of the washing machine/tumble dryer, and 1 shelf under the sink.
Storecupboards reasonably full, but I also use the space between the top of the cupboards and the kitchen ceiling for extras - pasta, rice, teabags, coffee, a few tins, spare biscuits - they hide behind the plinth there.
In the cupboards, I stack a few tins high, to fill the entire space. I use glass jars for rice, pasta, flour, dried fruit (raisins etc), different kinds of sugar, couscous, polenta etc. They take up space but because they are solid, seem to be more practical than loose packets (and keep things better because they are sealed). And are easier to move in and out to get something which is in the second row behind the front row regularly.
I keep packets of spices etc by taking the plastic pouches out of the cardboard box, writing with sharpie what they are, and then storing them all in a deepish plastic tub - I can fit about 15 Shwartz sachets in the tub in the same space that 3 Schwartx boxes would take up (so 6 sachets).
Extra wine is in the floor of the wardrobe in the spare bedroom.
The freezer is slightly groaning, but I know I could do it better. I use takeaway plastic containers to freeze single portions of leftovers or batch cooking, and some pyrex freezable dishes for lasganas etc - so they all stack together well. I use Ziploc bags for meat or veggies, which means I can get rid of a lot of air - I tend to remove chicken breasts from their plastic packing to freeze individually and sometimes I will dice some before freezing - that saves a LOT of space from the plastic container, and also means they are somewhat pliable to fit into small spaces (although I try to freeze flat to stack better - as freezing into small shape holes can be problematic when that shape later changes....). And for stock (that I make occasionally if we've had a roast chicken etc), I tend to use tall thin cartons like the 500ml cream cartons, which seem to use the space available better.