I believe anyone doing real estate photography that doesn't also have a real estate flyer, postcard, brochure and online tour product is missing an opportunity to add profit to a shoot. Listing agents need a flyer for each property they list. Most will mail between 100 and 300 postcards to the neighborhood where the listing is. If it's an upper-end home ($800,000 and above in Seattle area) many agents do a 4 page fold-in-half 11x17 glossy brochure.
I know, what's holding you back is you don't feel that you have the graphic design skills to create flyers, postcards and brochures. Well guess what, there are companies like Imprev that make professionally designed templates, so creating a elegant postcard, brochure or flyer is little different than creating a do-it-yourself tour. You just plug-in the photos and some marketing text and you've got a print piece.
There are many companies like Imprev that have flyer, postcard and brochure templates but I am pointing out Imprev because I've used their service several years ago and think they do a particularly good job of graphic design. The way they work is you pay a yearly fee to use their templates. Here's the Imprev price sheet. They have many more products than just print templates.
Can agents do this for themselves? Sure, some do but they are in the minority. 99% of agents would rather have someone else do this for them than do it themselves. Also, the agents that are likely to hire a photographer are the same ones that are likely to pay a premium to have high quality flyers and brochures. Adding this to you product list could easily add several hundred dollars profit to your shoot.