I picked up some easy inspiration today from THIS POST at Temple of Demogorgon. He’s one of those OSR kinda folks, but I shamelessly stalk those guys as well as everybody else for great ideas. His post struck me as a monster that deserved a 4E conversion, so here it is– a Large Giant Spider that basically is a minion factory.
Basically, imagine the she-spider below about the size of a Kodiak Bear, using one of its many legs to fling baby spiders about the size of a housecat AT YOUR FACE.
I imagine this spider as the companion to a spider themed adventure or Side Trek, possibly among a colony of other spiders, drow, aranea or ettercaps. Basically, anything that can give this monster a chance to spew forth a bunch of nasty, poison-vulnerability-causing Spiderlings before the PCs realize the threat and crush it. It should open the combat with Rain of Spiders and then keep punishing the PCs for not killing it fast enough by making more and more minion spiders.
I present for your eight-legged horror the Colony Spider and Spiderling!