The hardware engineering industry as a whole tends to look at the tools and tool extensions they use as "Critical IP" or company trade secrets, so such things are not often shared. In cases where tools and tool extensions (add-ons) are publicly available, they are usually commercial software and are fairly expensive.
Personally, I simply do not have the resources, ability or interest needed to sell software and run a software company. Due to sleeping disorders, providing 24-7 support or even scheduled hours is physically impossible for me. None the less, I still do the things that I do well. I write code. I solve problems.
Though a lot of the professional work I've done is proprietary and can not be disclosed, I still own the rights to my own personal programs. Of my personal store of programs, a lot of them were written as favors to friends in the industry, which is how the programs came to be well used and well tested in commercial environments.
I've been told an unconfirmed rumor that some of my code, particularly some the types of checks done by the Destubifier, has actually made it into the current Cadence release (SPB 15.51). Though it is true that I sent out pre-release code to a few Cadence employees, there is really no way to confirm or deny the rumor either way and more importantly, it doesn't really matter. If this rumor is actually true, I'm just happy to know your designs will be better due to my efforts. All of the code in the project releases is very specifically licensed so it CAN be used in closed source proprietary software products.
Making the programs freely available to you will hopefully <sarcasm> make me famous </sarcasm> or at least it might occasionally serve as a reference for more contract work while helping the industry as a whole. Through my goals are generally altruistic, making my work freely available holds a very remote potential of being personally lucrative sometime down the road but that's just how altruism works; the benefit of being kind is being remembered for your kindness.