I recently purchased a property management company here in San Jose. It has about 100 contracts, but it's the Bay Area, so the revenue is a lot higher than other parts of the country. Gross Management Fees are about $18,000/Mo. Commission split with my Broker is hard, but it caps at about $40,000/Year and it also means that my real estate transactions aren't split because I've already capped.
One thing that's nice is that it's consistent and steady. There's a decent amount of turnover of clients selling property or taking over management when things have been stable for a long time, but we keep pretty steady. In Real Estate, there are dry spells when there are no listings, but with PM, you know more or less what's coming in each month.
It's also delegateable. I hired an assistant to handle all of the tenant and maintenance issues, which is about 80% of the work, leaving me to deal with the owners and keeping an eye on the big picture. He costs me about $6,000/Mo, but paying 1/3 of my revenue for 4/5 of my work is a good trade. Also, it means there's room to grow. When it was just me, I was practically overrun and I had to turn away new clients because I couldn't handle them.
As an agent, it's also nice because you have a good shot at the listings when your clients do sell.