If you guys are enjoying those sample Microsoft interview questions, you'll love Cracking the Coding Interview. I've been reading it to prep for an onsite at one of the tech giants later this month.
This site has a ton of interview questions too - you can filter by company and programming language.
Read it a while back, and still go back to it from time to time. It's a good resource. The Kindle version is a little janky fyi. I have never interviewed for a tech giant, but I can tell you that similar questions appeared in a interview I had at a smaller company, so it is useful outside of that.