Being a Java programmer and having worked for the top MNC in the world and having been associated with some apps, I have come to understand that just limiting your knowledge to programming will never make your money. May be you might get lucky to some what extent in freelancing. But the true money where you will be paid even when you are not working is apps.
Buying and selling domain names is another way to make money from home and requires very little investment or time. You can buy domains at their registration prices or even cheaper and trade them at a profit. However, always research on sites such as sedo.co.uk, afternic.com, ebay.com or other domain auction sites to get an estimate of the hottest selling names. The best way to find good ones is to use terminated domain lists, which contain several expired names that are back in the pool.
How much will you make? I think my best month with Google AdSense was almost $5,000 over the last ten years. That amazing month blew my mind since it was actually near the beginning of my blogging journey. When you go from making zero to $5,000 in a month, that will rock your world. For me, it also got me even more excited because I knew there were other ways to monetize.