Less-than-common home wiring systems?
Sure.  Low voltage systems have a lot of versatility.  You can put a battery on them, so they stay up when the power fails.  You can add solar panels, so they stay up in long outages. Many routers and DSL/cable modems actually want 12VDC (the network stays up because the central office has batteries/generators).  It's easy to charge phones and tablets from 12VDC.  LED lighting is not a problem at either 12VDC or 24VDC (light strips and "bulbs" intended for RVs.)  

For heat, furnace controls can be managed either by switch-mode synthesizing 24VAC or finding components happy to run on 24VDC, including smart thermostats.  Or Empire-style furnaces don't need any electricity at all, and this can be a backup furnace, with a plan to close off parts of the house it can't heat.  A refrigerator could be modified so its 120VAC inverter only runs when there's a cooling call.  A simple gas stove/oven doesn't need electricity either.  You could make a home fully functional in power outages, complete with internet and media streaming.  

That pretty much describes my next house. 

However, as you may know, NEC prohibits low voltage wiring in the same conduits and boxes as 120/240V unless the boxes are subdivided with approved dividers. Non-conductive fiber-optic is OK.  Also you are not allowed to hang "other stuff" on the outside of 120/240V power conduit, raceways, busways etc.