Background - I'm playing a Rakshasa-spawn Tiefling Master Summoner. I'd like to specialize in summoning evil, particularly Outsiders, but the current lists for Summon Monster aren't terribly weighted in that direction (and as far as I know Paizo hasn't released any expanded lists since the new Bestiaries came out? I'd love to be wrong). Summon Good and Summon Neutral monster feats obviously won't help me out here and I can't seem to find an evil equivalent for the feat - yet, anyway.
So, by RAW, do I have any options for expanding my summon selection? 3.0/3.5/3pp stuff is acceptable so long as it isn't ridiculous. I was contemplating trying to just find a comparable scale for each level of the spell and add those options to the list, pending DM approval of course. This link is what I'm thinking about using for a guidepost. It suggests the following for appropriate CRs for SM levels:
SM I: ½
SM II: 1
SM III: 2
SM IV: 3
SM V: 4-5
SM VI: 5-6
SM VII: 7-8
SM VIII: 9-10
SM IX: 11-13
Thoughts? Other options for increasing summoning lists?
Nope, sadly summon monster has gotten the short end of the stick in terms of bestiaries and manuals beyond Numero uno.
That list of CR's you got there is a decent way to measure monster power level for the spell levels, but note that there is a little fluctuation beyond the numbers there, such as CR 14 monsters in the level 9 list.
AS a GM I allow my players to use custom summon lists by my acceptance, every monster raw from a bestiary, pathfinder only. The system is simply that you may remove any of of the summons from the list, then substituted your picks instead. The new monsters must be of equal or lower CR to the replaced ones. In the case of outsiders the summoned creature must share at least one alignment element with you (So to summon a Devil you must be lawful or evil).
This method lets you summon whatever you want, without increasing the number of options, theoretically without making it more or less powerful.
Dino obsessed monster mash, (Summon monster 4).
Removed: Hound Archon (Cr 4).
Added Pachycephalosaurus (Cr 4).
I hope this gives some inspiration.