I probably spend too much time on Meta.
Some interesting Stack Exchange Data Explorer (SEDE) queries of mine:
- Cross-Tag Tag Usage Breakdown
A breakdown and usage count of each and every tag used alongside the given tag on posts.
- Anonymous Vote Counts and Adjusted Post Scores
Ever wonder where anonymous votes go?
Pulls all votes by anonymous users and users without the respective voting privilege and aggregates them by post voted on.
- List of Average Question Scores Per Tag and Average Score of All Q's & A's in [Tag]
Gets the average score of all questions using a given tag. The first query pulls all tags, the second pulls a specific tag.
- All Vote Totals By Year-Month
Timeline of votes (up, down, total) cast on the given site.
- Total Users By Year-Month
Total new users that joined [site] each year-month over the given site's history.
- 100 Most Duplicated Posts on [Site] and Duplicates for [Post]
Lists the 100 most duplicated posts on the given site; the latter query lists every duplicate of a specific post.
- Timeline of Questions & Answers Posted per Month
Totals of the amount of questions, answers, and questions & answers combined posted on [site] over time, grouped by year-month.
- Comment Length Popularity Breakdown
Groups all undeleted comments by length.
(Did you know that the most common comment length on Stack Overflow is 61 characters?)
- Most Voted on Q & A Posts in [Date Range]
Pulls the most voted on posts on [site] in the given date range.
Especially useful for finding the most popular or contentious posts in a specific time frame.
- New Comments on Older Posts
Pulls a list of "older" posts with "newer" comment(s).
(Probably most useful for exploring site Metas.)