Some great submissions here, nothing as nice from me, but I guess there is something to learn from most people. I have created many in my life, non of them ope

Some great submissions here, nothing as nice from me, but I guess there is something to learn from most people. I have created many in my life, non of them open source (yet; the one I am chewing on now will be I think), most of them toys, the most successful one really niche and those same successful ones embarrassingly crappy. I wrote a PHP before PHP (in Perl as well, guess it was meant to happen :) and it made me a lot of money being able to write dynamic web applications without much of the plumbing at the time. I wrote a bunch of 4GLs for finance and web CRUD applications, all sold as addons to our CMS early 2000s. After that I wrote a lot of toy languages which I meant to put on github some time but I don't think they are of interest to anyone anymore by now. I write, for my own sanity, Forths when I do embedded work, assembly work and/or work that doesn't allow me to have interactivity for development. They 'why' is easy; the feeling that things are just not as efficient as they can be and the drive to do something about that. That will never leave me and it did give me a lot of competitive advantage over the years. Mostly in the end I end up with something that, after postmortem, would've been easier with Lisp. If I surpass that point in my life, I succeeded.