I think that with the advent of the compact disc there are many people who work in the audio industry who make their whole living dealing soley with the past.
The main "professional" thing I do is restoration and mastering of old Punk stuff for either re-release or as a retrospective release. I joke that my resume is begining to look like I stopped working in the late 70's or early 80's.
I find this work to be generally rewarding because as a fan I love the music it's self and as a musicologist I feel like I am helping to set history right.
As we speak I am listening to what should be the upcoming Terrorists release.