Many moons ago, I built:

A neural network that would recommend buy & sell signals on various stocks in a hand-picked index, that had an invite only daily newsletter called "Justin's Junkmail." I made some good money from putting one ad that I hand selected into each newsletter, at the footer. The entire thing ran almost on auto-pilot, other than me fussing over the wording of the auto-generated recommendations and which ad to let through for the next week. The newsletter mailing list grew organically, and without any prescience, just prior to the dotcom bust, I sold the mailing list and software that ran it for "a nice sum of money." The new owner drove the entire thing in to the ground - but that's a story for another time.

A year later I wrote a neural network to pick the winners of horse races, with a piece of software you could download, and also, again, a daily newsletter that grew organically. The newsletter contained information on predicted winners at select races, previous day's results, and how accurate the predictions have been for the past 24 hours, the past month, and for various jockey, trainer, horse and track combinations. The newsletter drove the sales of the software. I sold that entire package for "a nice sum of money" back in 2004-ish. It ran on auto-pilot pretty much, other than having to deal with refunds, and the outsourced worker I had entering all the race data manually (to get around a website scraping licensing issue) not finishing the data upload in time for the newsletter to publish.

I built a small business website that would match borrowers (business owners) with lenders (private and institutional investors, banks, equity credit), and that made "some pocket money" each month, and ran on auto-pilot, other than having to deal with the usual IT issues of a website written in VisualBASIC and running on IIS, which I eventually sold "for a nice sum of money" back in 2008 (which unfortunately was used to pay off some debts of my video game studio).

I built a clutch of mobile friendly funny videos websites, with hand selected ads, that ran on auto-pilot. Unfortunately I abandoned it due to bad advice from a business partner. I now wish I had fired my business partner (or never got involved with him) and kept working on the websites.

I currently have a country-wide (United States) information website on licensing requirements, job opportunities, training facilities, and career advice, which runs on auto-pilot other than me coming up with a dozen topics to write about that month, which is really just me trawling through two or three popular web forums on the subject to find out which questions are hot that month, and then I outsource the writing work for the articles. The website makes "lunch money at a nice boutique cafe with over-priced soup" after all expenses (several hundred dollars a month for writing and graphic design) are taken out and has been running for about six or seven years now.

I have a whole bunch of videos (1,500+), not under my personal brand, that I've created that make a few hundred dollars in ad revenue each month that I, fortunately for the viewer, do not appear in. I'm simply the voice over.

I am currently working on another idea...