Achievements or Badges
I think it would be great to have some sort of achievement or badges added to your profile when completing different types of batches (i.e. Census, Birth, Death, etc.). Then, the person could share their badge on Facebook, or other social media, and their friends would ask, "What is that?" and then they could check it out.
There could also be levels within the badge. For instance, if they have their Census badge for doing 1 batch, they would have a level 1 badge. Then, if they hit different benchmarks, the badge would be different levels, with a different graphic. Like, if they indexed 1k, 2k, 5k, 10k, census records, the badge level would increase. This would also encourage doing different types of batches so that users could get a "coveted" badge.
You could have different kind of badges, even like how many years of service.
The gaming platform Steam does something similar with Badges, and Leveling up your profile.
I've included a few examples below from Steam.