I ran across the CareerCup website which says they can help prepare you for programming interviews with various US based top tech companies. They don't "guarantee" anything, and the site appears to be backed by a well reviewed book*.
*The reviews are on Amazon
I have been an active member on StackOverflow so according to me best resource for preparation would be StackOverflow. But I saw that CareerCup has collected interview questions from various companies. So the key difference is that I would have to dig for interview questions within SO versus having questions already aggregated by the other site.
How do I go about evaluating the credibility of a website like this?
How can I evaluate if their interview preparation offerings are worthwhile?