I think it's time to finish off this set of posts before the title has to change to 'Thirty-One Years of Experience'.
I started off trying to work out how much use thirty years of programming experience was really worth, given that so much of it was in technologies that are no longer extant. I've come, sadly, to the conclusion that much of the first fifteen years or so can be safely skimmed through by anyone reading my CV. In the field of Software, specific knowledge of languages, libraries and operating systems dates all too quickly. If you're not constantly learning new technologies, you can end up fit only for maintaining legacy code.
And yet I still hold that I've gained something from having programmed since 1980 that I wouldn't have now if I'd only started in 2000. Thirty years of debugging have given me an intuition for tracking down bugs, to the extent that sometimes I can't even explain to myself afterwards how I got to the solution. I believe this is because debugging is quite often a logic problem, and practice makes you better at it irrespective of what language or platform you're using.
Over thirty years I've seen trends come and go, supposedly 'killer' languages have their day and then fall away (Ada, you promised so much!). It would be nice to say that my experience lets me spot which upcoming technologies are the ones to follow, and which are going to fail, but that would be untrue. I write as someone who once learned Forth.
In the end, it's not so important how much my experience is worth. The bottom line is that, after nearly three decades in the field, I still feel as I did when I received my first pay packet back in 1980: that it's a nice life when you get paid to do something you'd willingly do for a hobby.