For example, if you are in a heavy bike community, maybe installing bike racks somewhere might bring some character to the property and it doesn't cost a lot.

If you see very low appreciation in 4 years but rack up astronomical operational costs much of what you accomplished is working yourself in the ground for no apparent reason.  

Probably replace the wooden porch down the road sometime but happy with my purchase.

I've seen deals that are "rack + $0.03/gallon" and others that get much better deals. 

Here is a breakdown: Queen bed frame: $400 - $700 High-quality mattress: $500 - $9,000 Pillows (2-4 per bed): $40 - $120 Linens (sheets, duvet, comforter): $150 - $300 Blanket: $50 - $75 1 Bedside tables: $40 - $150 1 Lamps/lighting: $40 - $75 Art decor (2 pieces): $100 - $275 Bathroom towel racks, dispensers and soap racks: $100 - $200 Makeup mirror: $20 - $80 Hair dryer: $20 - $60 5x7 rug: $75 - $250 Small vase with plant: $20 - $50 3-ft decorative tree: $50 - $150 Two window curtains (with rods): $80 - $150 55-inch TV: $375 - $500Total cost per bedroom will range from $2,320 - $3,545 

As Jay mentioned, massive power requirement that will not get cheaper in time, and along with large water requirements for cooling the rack systems, so targeting locations that provides these necessities is key.

HOA violations or fees racked up by tenantsF.

@James McGovern, while I don't necessarily agree with your language, I certainly understand where you are coming from.If you truly want to exploit them, then continually report code violations: long grass, broken windows, broken down cars parked on property, anything that will keep racking up the nuisance issues of the property that the landlord not only has to handle with effort but also with money...But, assuming you don't want to go to that level, find the owner and reach out.  

I use mine for storage of beach toys, drying rack for swim suits, storage of extra supplies and on occasion it’s an extra parking space.  

If you see old wooden windows in a multi family building, it is very likely to contain lead.