Furnace filters, duct cleaning, dryer vent cleaning, chimney cleaning, fridge coils, swamp coolers, gutters, ac, sump pumps, plumbing inspection etc etc.We are toying with the idea of paying for a separate independent inspection annually. 

When the inevitable happens and you have a sink or dishwasher leak (you won't have a fridge leak because you should never connect water to a fridge.

I'm an investor but in my teeny home kitchen (8x8) we put in a dishwasher AND a wine fridge. 

It just takes an almost fanatical persistence to neatly caulk up all the cracks in crevices and place your powder and poisons in behind each outlet wall plate, behind each oven or fridge...under every cabinet, in any nook and cranny (there can be no hiding places)...At one point in my research I called a local exterminator and went through my ideas, and he was like "Man, you got this.

A new garage door opener, a fridge and a leaky faucet. 

They also have the tenants provide appliance such as fridge and washer/dryer. 

The first time someone breaks in and takes the fridge it will pay for itself when combined with the insurance discount and the tenants will really appreciate it.With all the  pitfalls and hidden costs even if you get a good tenant it will be more profitable in the c neighborhoods.Make sure to but on a block without too many border ups and has no stores on that block.Good luck if you go this route. 

Here's what I generally pay (remember, this is my area, my contractors, etc, so it may not be apples-to-apples in your area):Water Heater plus Expansion Tank: $125 (done by plumber)Gas Range: $25 (done by plumber)Fridge Water Line: $15-25 (done by handyman)Dishwasher: $75 (done by plumber)Garbage Disposal: $50 (done by plumber)Built-In Microwave: $40 (done by handyman)Washer/Dryer, plus Venting: $25 (done by handyman)Oftentimes, my project manager will do most of these things, so it's actually free, but if I'm paying my contractors, this is about what I expect.

I've never had anything happen, except for getting into a shouting match with a non-paying tenant, when I found her with the fridge on the front porch, trying to sell it.

All utilities are separate and could be payed by tenant, but there are no appliances (fridge or oven) in either unit.