I agree with what others have said; this is a great question. I think there are a few answers (most of which have already been touched on at least a bit) which complement each other:<p>* Open source whatever you can. I have had the good fortune of being self-employed for the last few years (although I was also in school for part of that time), and one of the huge benefits of that was being able to open-source almost everything. (My client agreements usually allowed me to open-source anything that wasn't unique to their line of business.) Obviously not everyone is that fortunate, but it often makes good business sense to open-source internal libraries and such (more eyes on the code base, currying favour with developers, etc) so it definitely can't hurt to ask and try making a case for it.<p>* Take screenshots and video. Sure, maybe shallow by themselves (especially if you're not a UX/front end person) but it is a neat part of the package, even if only for yourself to review 10 or 20 years down the road. Some people have pointed out that you may need permission to take a video of the software... it seems to me that if you were working on that sort of software you'd know it.<p>* Keep a journal. This is helpful on a lot of personal levels. You might also want to blog, for similar reasons. 10 or 20 years down the road, it will help you remember what you did. Information from the journal can be helpful in portfolios and resumes, and you might also find yourself using your own journal down the road when you run into similar problems.<p>Regarding your second edit, I think turning the above information into a "showcase" probably just means building a small portfolio for yourself. Have "case studies" where you talk about what you did for a certain project/company/whatever. Or, depending on the nature of the work, you might choose more of a "memoir" style--either way, the point is you pick a few things you worked on and write about them, using your journal (if available) as a memory aid and screenshots/video/open source contributions as supporting material, if available.