Professional landlords: What are ways to increase our top line?

[Nicholas Nicastro]

Like many of you, I have > 100 residents paying rent to me each month. This is terrific. 

But with rent being set, I often wonder if other landlords have found ways to find incremental increases in revenue (that likely flow directly to the bottom line) with our captive audience? 

I presently receive $0 from any utility company, vending company, or other third party. Do any landlords have setups where we can profit from these things? Buildium sells renters insurance directly to our residents but sadly we do not get a cut. (not even sure if paying us a commission on insurance is "legal")

Or are there products / marketing techniques we can use with our captive audience (without spamming them?)

The older I get the more I think I am wasting the 1000s of people I have rented to and not captured any incremental revenue. Any thoughts are appreciated!