The 'Posts per page' setting in posting > post setting of the ACP. I think it should be a per forum based setting, for each individual forum. Just like the 'topics per page' setting is.
On 3.0.12 I had a mod that enabled me to choose 5 posts per page in three of my forums where people posted lots of pics. Having now upgraded to 3.1.1 the search engines will wonder what's going on with the different pages/pagination for all of those topics.
I have requested an extension Here...But I'd hope that this can be in the core. I would really love it myself as I'm sure others may?
Discuss.