I've been confronted to a lot of zerg players only playing zergling rush and it's pretty annoying. I usually play terran and I have a lot off difficulties countering these.
The best thing I found was this build which helped me countering the rush and the next wave until I had enough units to attack and beat him.
What is the best build against a Zerg, keeping the zergling rush in mind ? (feel free to post protoss solution too. The best zerg solution is ... wait for it ... zerglings !)