In early 2010, I wanted to read some tweets I posted a while back. It sucked. Twitter wasn't made to do that. So I made it easier, and launched TwimeMachine (http://twimemachine.com/
). From just one blog post, it grew organically: people searched, and people talked about it. Over time it has been used by 585 000 Twitter users, including big names such as Paulo Coelho, ESPN, NBA & Cesc Fabregas. It was also recently recommended by the European Council as a useful social media tool that they use.
I haven't done any substantial work on it for at least a year (and not really interested either). Since I'm bootstrapping a new company, I'm planning to sell it, to get additional padding. https://flippa.com/3095486-successful-social-media-tool-with-40-678-uniques-mo-used-by-nba-espn
It doesn't make much, but costs less than a beer a month to run. It's a good fit for a digital agency or a social media management company. If you are interested, or know anyone who is interested, send it along!