Ask HN: Passive income ideas?

I can code well and I have 1-2 hours daily that I can spend on any project/activity that will, after some work, generate $1000/per month net in passive income. I have kept the number at 1000 as my hours to spend are limited. Change the number if you think I can have a bigger passive income with the amount of time I am have. I would like to hear ideas from the community, specially from folks who have done this in the past or are doing this currently. Please give concrete actionable ideas.

EDIT: I am willing to learn anything.

I've done this through licensing SaaS to social gaming companies (apps). It took a fair bit of work though -- I'd say 6 hours daily.

Work someplace. Live frugally. Don't spend the money. Leave it in term deposits or other low risk, relatively high yield (ie. at least above inflation) locations. Rinse and repeat. (Recently, I heard that Vietnam offers solid rates on term deposits in foreign currencies.)

I trade stocks as a hobby and have been able to make some money.

If you have any kind of social media following, you could exploit it with affiliate links.

Someone posted a good article about finding niches in the app store recently. Something simple that satisfies an unmet need could earn decent ad money.