I sell Steam Wallet Codes (gift cards) for Bitcoin. I've done over 1500 BTC in sales in the last year and make about 5% profit, depending on the current BTC/USD exchange rate.
I started the site as an experiment to build my own payment processing system and got lucky with the right product.
I spend about 5 minutes 3 times a day restocking inventory when I get an alert on my phone that stocks are low.
I've been experimenting with 0-confirmation transactions and hope to relaunch in the coming weeks with a service that emails codes in under 60 seconds.
One can make a bitcoin front for pretty much anything online. Where else do you see opportunities like this?
They don't have an API, but they do have a standard template I can email them to have them perform the action and they offer net-30 billing.
This will allow me to ask for people's phone numbers, select their carrier, and send me Bitcoin. Then I send the order to the fulfillment company who loads up the users phone account and I pay them at the end of the month.
I'm excited by it because everyone talks about how Bitcoin is good for the remittance market, but there needs to be a use for Bitcoin in the developing world for people to use it if they don't have access to an exchange and a bank account.
and in a few days you'll have a dozen clone sites to deal with...
I rarely hear from the property manager, he just runs large expenses by me, tells me when tenants are leaving and always has another lined up, recommends when we should replace carpet/appliances/paint, etc. My largest time commitment is during tax time since I still do our taxes.
For more detail see my post on 2014's passive income: https://news.ycombinator.com/item?id=8118022 The only significant change is that our property in San Diego has appreciated significantly over the last few years. When I wrote the comment above I hadn't looked at the current appreciation, but I was way off. One of our properties has approximately double in value from what we paid for it and the other two have increased by at least 60%. Rents haven't increased near as much, but we've added around $50/yr to the rent. The vacancy rate in San Diego is ultra low, so the market supports it.
Note: Some people say property managers aren't worth it, but the good ones are. We've had to fire a couple, but the one we have in San Diego now is stellar. We've never had a property vacant for more than a week or so. If I'm busy, it may take me a month to find a replacement tenant. That month of lost rental income more than cover property management fees, not to mention the headaches it saves me.
Created a website to help developers build muscle memory with their favorite editors and tools.
Launched on HN a couple years ago. Still pays for its hosting and then some :)
This was a scratch-your-itch project that started out in 2010 as a Heroku app that I threw together for myself. Over the the years I collected feature requests and eventually rewrote it from scratch and relaunched it as a paid service. It pays for itself plus enough money to buy myself new equipment every once in a while.
I have over 140 paying customers and lots more free users. This year I added support for Egnyte which should bring in some larger enterprise users. The system runs great with very little maintenance. I believe that faster expansion isn't possible or easy at the price level (advertising has been tried and proves too expensive).
Tiny web app for hashing strings using different algorithms.
It's really just a tiny project I threw together when learning CherryPy. Covers itself in hosting and provides a small bit of extra change.
A domain that earns via affiliate commissions. I write a blog post every now and again and swap in different offers from time to time. But it works very well for the amount of time I invest in it. The companies I work with offer lifetime commission on referred customers.
About once a week someone calls or emails me, and I just send them a standard email about what a VPN can do.
When I get particular good offers (Black Friday for example) I fire off an email to the newsletter which has about 200 subscribers I think.
The site takes less than an hour a month to maintain.
Low-cost, self-hosted PHP-based applications for small businesses that can't afford expensive enterprise systems. Built the first system (CRM) to scratch an itch, and it sold a few copies as soon as I put it up, so have expanded to other applications as well (ticketing / issues, documentation / wiki, HR / timesheets, etc).
Doesn't fully pay the bills yet, but making decent side income, and I'm hoping that one day it will be enough business so I can work on this full time.
An Android app for quickly accessing contacts, apps, and whatnot. It sits on top of your screen and if you swipe down from the little bars the app opens.
The income is mostly from the Pro version; about 5x the ad revenue. Extensions are 1x ad revenue, each. Themes made almost nothing, so they're all free now.
A simple web app that generates short links to Flickr Sets to automate the download of all the pictures with just one-click by anyone (even without a Yahoo account).
Got a lot of popularity with Flickr users to easily share album and download a backup of their pictures, it covers development and hosting costs with a bit to spare.
I have more than recooped all my coffee money with it.. LOL
A task tracker / outliner with a Vim-like editing mode that I built for myself a few years back. It gained a lot of popularity through HN and Lifehacker.
I eventually rewrote the application and offered extra features and mobile support for paying subscribers. It now pays for date night with my wife.
I wrote articles all the time, not actively and mostly for myself. I make cash off stuff I published years ago and once in a while, one of my one-off posts that I don't even make for others to see hit it off and I make a bunch.