Considering winter is right around the corner, I would place these units strategically in corners of each room. Turn them on when it gets chilly. You can probably set them on a timer too so that your house is nice and cosy when you get back from work.
Also, if you have a newborn at home, they make a very enjoyable background sound that will soothe him/her to sleep.
While the ASIC heat is good, I'd say ASICSs are too noisy to be really kept indoors, especially with a baby in the house.
If i were the OP and had already gotten ROI on the machines, I'd sell them already. There doesn't seem to be much development on litecoin and simply expecting it's value to recover would probably mean that the entire crypto market will recover better. Simply sell the machines and buy the coins!