Ken here, yet with another conjuration suggestion. Sorry, fellas!
So, this is something I've seen employed in other servers, and I think it might be a neat concept: Summoning Streams, aka making the summon monster spell call up something specific.
For example:
Let's say it's a feat you pick : Summoning Stream (Creature). Said creatures being iconic to gothic horror and/or the server in general. Bats, wolves, spiders, ect....maybe some more esoteric ones, like Scorpions?
Anyway, once you pick up the feat, the summon monster feat should only let you call up that kinda critter. Frankly, you don't even need to implement other stats. Just use the regular summoned monster stats and replace the model with the creature specified.
With perhaps a few different models in the later tiers? A blade spider or one of those queen spiders at later levels would be neat, and pants-shittingly terrifying.
Some might go 'so a feat that basically just does a cosmetic change?', well, not entirely.
For one thing, maybe differentiate the critters just a bit by giving slight bonuses? Spiders/Scorpions getting a poison attack, Wolves getting a +2 STR bonus, ect. Stuff like that.
As well that, it would make higher tier conjuration more viable, as you wouldn't be calling up elementals anymore. Granted, your summons would no longer get benefits from the Enhanced Elemental feats, nor would they have the DR and immunities that elementals have, but that's a fair price for safe summonings, I'd wager.
But beyond that, I think this would help with solidifying characters. I know of at least a few sewer dwellers who'd enjoy being able to call up super rats, I imagine.