Recently Runners World published in it’s magazine an article on strength training for runners.
The article can be found here.
Among some of the exercises suggested are:
Bridge:
Plank lift:
Side Plank:
In his blog Matt Fitzgerald also has a list of exercises you can do to strength train as a runner.
He recommends similar exercises as Runners World but adds some more. Like:
Dead Bug:
Single leg squat:
You can read the whole article in his blog.