yes, keep a portfolio
Yes, that's a good point. One of the problems that's always existed in the field has been extravagant praise and rewards for minor feats, and no praise or pay for brilliant, hard-won improvements.
We should keep portfolios of the features and tools and processes we've created or improved, the letters of commendation, certificates, awards, publications, etc. We tend to not keep track very well of such things and lose even the tangible ones... and then, when we need then, we're empty-handed, unarmed and we've lost track of our former co-workers, references, etc.