Powered recycle bin using the blum Servo Drive system. You can also do this with the Ikea version of the system in an 18" cabinet. Not a great amount of appliances in the 18" width except for dishwashers and ice makers.
Best of luck!

Here is a link that might be useful: Ikea version of Servo Drive

So you're saying like a slide out or tilt out bin for recycling, and then use the power device to push it out when your hands are full? Won't this have the same problem as the garbage compactor? That is, stuff gets behind it or under it, and then attract mice?

You could put shelves or a cabinet in, but use the countertop space above it for a built-in barbeque grill, deep fryer, or other such appliance, which are usually either 12" or 15" wide. You'll need overhead ventilation for most of those, or a downdraft unit to the side.

An ice machine is another choice - these make much better, clearer ice than the icemakers built into refrigerators. These need drains though.

All of the appliances mentioned are specifically designed to fit in a compactor space. The one thing that's rare is a warming cabinet, which is sort of like the intersection of a warming drawer and an airline service cabinet. They come built-in on Lacanche ranges, and I've seen them as free standing, but I haven't seen one in an long time and I don't know if they're being made. You could probably have one made for the price of buying one. They're very simple.

I like Lee676's creative suggestion.

If you haven't felt the need of a second dishwasher you probably don't need one, but if you don't have a newer model, you might want two when what you have wears out. The new DWs, because of their resource saving routines, mostly take more than two hours to run. A second unit (if the plumbing is easy to get there there) can take the pressure off when you're entertaining. Since dishwashers also generally use less water than handwashing, you might save water by putting in more large items, such as pots and mixing bowls, which many tend to wash by hand. You could have a whole dishwasher just for the pots! The newer dishwashers and new detergents are also friendlier to surfaces.

Another alternative, if you have a generally cool kitchen, that's not excessively humid, is a cooling cabinet. That's either open in front, or with a pierced, rattan or mesh front, to encourage air flow. Maybe even with a small fan. You can cool pies in there, or store your root vegetables (in basket shelves!), or whatever suits. Low tech, but useful.

Or you could make it a hamper for tea towels and aprons, but it would still need airflow to keep it from getting icky.

That's pretty much what kitchen appliances do: Warm/cook, cool/ice, or wash.

A Wine fridge is not to just keep your wine cold, it is to store it for longer than normal and help to preserve the taste. If your wife is keeping her wine in the fridge she is killing the taste of it, if it anything other than a dessert wine.

A wine fridge would be great there to store either whites or reds and keep them at the proper serving temp.

Ben,
The Ikea unit is not a trash compactor. For all intents and purposes, it is an electric drawer. It has two trash bins in it. It is really a great feature. See the Servo drive link below. You don't have to use the Servo Drive for just recycle bins. You can use it for regular drawers and make your cabinets handleless.

Here is a link that might be useful: Blum Servo Drive Overview