For a long time I wanted an inorganic chemistry based software. I would enter some reactants and the program would give the final products, based on a list of standard reactions.
But I couldn't find any such good free software. So I made one of my own. It doesn't have a very good user interface, but it works the way I want it to.
There may be many more people out there who want the program like me, but can't make it themselves. I want to make my software available to them for free. But how? Where to begin? I haven't the slightest idea.
My program is flexible. It stores all reactions in text files. Hence, anyone can make their own library of reactions, or edit mine if they want a different functionality. My reactions files work fine for qualitative analysis of an unknown salt.
Stick it on sourceforge. Google search for the problem that lead you to making this, chances are you'll find forums of people asking about it. Make an account, post a link with a description and then repeat. If you need help adding onto/making more usable I'm sure people here would be willing to help.