At the right side in Activity page of user, there is box heading "IMPACT" which shows:
- Number of people reached
- Number of helpful flags
- Number of vote cast
As well as helpful flags, I think reviewing is contribution for improving the site and moderation.
Review queues (also known as review tasks) contain posts that possibly need community attention, as determined by the system or other community users
Reviews show the contribution for finding + fixing stuff.
So, feature-request to add one thing:
- Number of reviews
And link it to all actions > reviews (?tab=activity&sort=reviews)