Wait for an Ajax call to complete with Selenium 2 WebDriver

I'm using Selenium 2 WebDriver to test an UI which uses AJAX.

Is there a way to make the driver to wait for a bit that the Ajax request will complete.

Basically I have this :

d.FindElement(By.XPath("//div[8]/div[3]/div/button")).Click();
// This click trigger an ajax request which will fill the below ID with content.
// So I need to make it wait for a bit.

Assert.IsNotEmpty(d.FindElement(By.Id("Hobbies")).Text);