I think at one point, if you have a shared password for a development DB, production DB, etc. then just keeping those on a pen and paper notebook is your best s

I think at one point, if you have a shared password for a development DB, production DB, etc. then just keeping those on a pen and paper notebook is your best solution. Usually, for shared environments such as that (although I hope the team can set-up their own DB's for development!), the number of shared "secrets" is relatively small. Some secrets are best not stored electronically, especially if they can give away user data.