Completely open source, no real marketing.
https://github.com/andrewljohnson/StopWatch-of-Gaia
https://itunes.apple.com/us/app/stopwatch-+-timer-stop-watch...
He has a wildly popular blog, and he is an affiliate for a few products, most notably, hosting. He makes 30K or more per month, from this one affiliate program.
He sells an ebook, something related to green architecture.
He also builds info sites, with Adsense on them and makes a few thousand from those.
He has a couple of iOS apps I believe, built with outsourcing.
As far as I can see, none of the above is passive or even close to passive (except may be the ebook). He worked hard to get where he is, and still does. He shares much of his numbers - good inspiration if you need some.
If you want some more concrete ideas, in lieu of copy/pasting a previous comment: https://news.ycombinator.com/item?id=5904316
I like the Excel idea a lot, I'm hoping to have several such questions.
Some random ideas I just came up with are below. Not all of them passive, but might still interest you.
- Website with WordPress templates for real estate agents.
- WordPress multisite network that enables real estate agents to create a site quickly and then pay a monthly hosting fee. You could scale this by selling to different real estate companies, getting all of their agents a personal site.
- Mobile marketing for restaurants. Create a service that enables restaurants to send text message deals to customers.
- Pick an audience that interests you and post user generated content. Then sell ads/sponsorships to companies that want to be in front of that audience. For example, if you create a site for people to submit cute dog pictures, a company like BarkBox might pay for sponsorship.
- Teach people a skill and use Amazon affiliate links to the tools that you use (if possible).
- Marketing analytics. Build a tool that integrates with Google analytics and provides recommended actions to take to improve website performance.
- Create a stock photo site for a specific niche (doctors, lawyers, start ups, etc).
- Create a directory for a specific niche and then sell top placement on that directory.
- Create a site that allows people who don't know how to code to make an app.
I used long codes (short codes are expensive!), and I didn't do the marketing myself. It's basically a way for them to keep a list of customers, enable automatic signups by texting the number, etc. They write their own messages and send them out.
I'm not much of a salesman, but I was able to make a few sales, mostly to local places via in-person conversations.
Anyway, I have this software built and I'm willing to talk about moving it into other niches.
Some open source project ideas:
- subscription commerce (open source birchbox model)
- location based platform for mobile apps (open source Uber/Lyft model)
- host your own airbnb page (open source airbnb)
etc..
essentially, any type of successful business model that can be replicated in other industries, open source it, then monetize on templates.
The entry level commerce space (shopify, opencart, woocommerce, etc) always feels overcrowded, but few things really nail it.
Opencart is the only truly free service that's a contender, and it's terrible. Granted - ecommerce, especially security, is very difficult, and asking for that in a free product is lofty.
If you can build a commerce platform that's as low-investment as opencart (read: free) with the UX quality of shopify, and just let it into the wild, you can make an absolute killing by owning the plugin and template market associated.
Ancient, but here's a blog post I wrote with some ideas: http://www.puremango.co.uk/2010/10/ten-ideas/
And Jacques Mattheij's post that inspired me: http://jacquesmattheij.com/My+list+of+ideas+for+when+you+are...
Second revenue stream for this - there are lots of "end of the world preparedness" sites (think of the people who are buying Glenn Beck's gold coins and you've got an idea of the demographic) that would pay to advertise on a website that attracts people who want to buy their way out of future-phobia.
I have a few other ideas in that vein, but I am curious of any traps that may be encountered.
Then see if that country or region has a dominant job board/classified website/real estate listing etc.
Millions of users are just coming to the internet in those countries and have room for growth. Many of the existing websites offer horrible experience.