Yes, this is the era of multiple resumes. But we may forget that every time we develop a new niche or what for us is a new area of expertise, it's often useful to create a whole new resume. That showcases our talent, experience, and accomplishments in that field in a very direct way.
For example, I have been lucky enough to land a lot of assignments in financial writing. Of course, now it's necessary to put together a resume just for that. Instead of employers' having to hunt through a more generic resume for what they need to know about my track record in financial writing, I put it right there in front of them.
But for the employers to get to clicking open the resume, we have to have a strong cover letter. That should be frontloaded with recent accomplishments. Those should then head right into what we can accomplish for that particular employer. The new game for employers is: Hey, applicant, what can you do for me, from the get-go.