I launched a side project in 24 hours last month (which I documented here: justinmcgill.net/24-hour-product-challenge-twist/).
It is called LeadFuze (www.leadfuze.com) and it's an email prospecting and outreach service that generates leads via email. Good for B2B businesses and startups, or even companies looking to validate ideas.
I've managed to hit $1k/mo ($1,100) in recurring revenue within 30 days. Going to be a much bigger focus of mine now that it is gaining traction.