I don't think being in multiple fields sends the right message to the consumer. It is challenging to get business, but now more than ever we need to be focused. We need to focus on selling real estate and if you can't get clients then it might be time to move on to a new industry. All the best.
As Melina pointed out, I would not create conflicts by creating ADDITIONAL revenue from a transaction though these real estate related channels.
HOWEVER, there is opportunity to leverage the vast enterprise most real estate professionals have created to establish passive income sources. If your database has the appropriate granularity to identify who you are communicating with, the opportunities become really attractive. I would suggest 'Jack and Jill' trades that help people, which is why most of us are in real estate.
I'm not a fan of the mortgage broker/REALTOR combination myself. That has way too many conflicts of interest for me. Clearly I am of the opinion that you should stick to one career and do it well.