Buying/starting real estate-related businesses

I own a few properties, and I've wanted to really put my knowledge of taxes/business to work for me. I've been wondering if anyone here has done much with buying or starting businesses that are related to the real estate world, even if tangentially. For example, if you own a number of SFHs and pay for lawn maintenance, have you ever considered purchasing/actually started a lawn maintenance business? Maybe you realize how insane of a margin you imagine floor installation companies are getting in your area and want to join in? Whatever your reason, I'm interested in hearing about it. I'm also quite interested in further exploiting the tax benefits of owning a business (rather than paying yourself a high salary as the owner, push money into a 401k to lower your tax bill, etc.)