For future reference (for me)
query 1 (average replies per person): select postusername,avg(thread.replycount) AS average_replies,count(postusername) AS threads from thread group by postusername HAVING threads > 10 order by average_replies desc limit 25;
query 2 (total threads per person): select postusername AS user,count(*) AS threads from thread group by thread.postusername order by threads desc limit 25;
query 3 (total polls per person): select postusername AS user,count(*) AS polls from thread WHERE pollid AND open!=10 group by thread.postuserid order by polls desc limit 25;
query 4 (threads each person has posted in): select username AS user,count(distinct(threadid)) AS threads from post group by post.username order by threads desc limit 25;