This idea isn't new, but so far I have only found it in answers or in more complex feature requests. So I want to propose this small (and hence hopefully doable) change to the site:
There should be a page which shows the number of questions in the close vote queue by tag.
This proposal is inspired by this post in the current burn down activities: From that post, I was made aware of a tag that needs more reviewers, and where I actually have the knowledge to do this. So the purpose of the proposed page would be to attract reviewers for tags which need them most urgently.
What is probably important for the implementation is that these number could be cached. They neither need to consider any overlap between tags, nor do they need to reflect how many questions are actually reviewable by the current user.
The information could for example be presented as shown in this UI mock-up, but really just a flat list would already be helpful.