@OP:
I don't know how much I can contribute to you since I am more involved with hiring experienced programmers, not new grads, so some parts of my interview procedure may not apply to you.
1.)
For one thing, I try to hire "programmers" and not "Java people" or ".NET people". By this I mean I am more interested in people who are good in general, even if their expertise is currently not in the field that I need to fill-up.
For example, if it were down to two candidates for a PHP job, and one was a "PHP programmer" while one was a programmer with very little PHP experience, but has a ton of experience in .NET, Java, and other crap like Python or what have you (scenario: lots of cool things except for PHP), I would most likely get the guy with little actual PHP experience. His breadth of knowledge (this is assuming I've determined he is actually an awesome programmer, and it just so happens he did not like PHP much or didn't need to before) more than compensates for having to send him to a 1-month PHP training course - which he will undoubtedly pick up on fast anyway. In fact, after that training, I'm sure he'd be a better PHP programmer than that other guy whose only experience was 5 years with PHP.
I suppose that for you, what this means is do not be afraid to expound on your other experiences other than the actual language involved in the position you are applying for. If it's C#, go ahead and show them your skills, but if asked about your past experiences, don't be shy to recount your other exploits in other languages. If they recognize you are an awesome programmer - and you just need training for you to fit in the team at first (this is the case a lot of the time anyway) - then you will get hired, even if you were up against people who may have better C# experience in their resume. At least, if I or my peers interviewed you, anyway.
2.)
With that said, you need to practice being interviewed. I am not kidding, unfortunately. People usually take it for granted, and will just "wing it" when the actual interview happens (this is ok for professionals who've been at it for a long time; for a new grad, not ok). Don't. Just don't. Instead, practice. And when you practice, you should be sensitive to how you come across - not too arrogant, not to shy, and definitely as enthusiastic about programming and work as possible.
The best way to do this is with a friend. Write down some guide questions for him (simple ones like "What's your C background?" "What is the extent of your Java background?" "Can you tell me about the most challenging programming task/problem you've encountered and how you solved it?" "You mentioned 5 years of programming experience in your resume, can you summarize those for me?"). Then let him ask you those questions at random, and answer them as best you can. You will never be able to practice ALL of the questions that the real interview will actually ask you, but you'll get the "essence" of a lot of them, and you will come across as more confident during the interview.
There are no right/wrong answers of course, since what you are practicing is mostly resume and past experiences stuff. But practicing will give you the opportunity to refine the way you answer.
Again, be sensitive about being too shy, or being too boastful. Sometimes, the difference between being "matter-of-factly" and being arrogant is just a couple of words, so be sensitive to those when you practice so that when the real deal comes, you come across only as "matter-of-factly" instead of arrogant/boastful.
3.)
Current events in the realm of programming or open source. It can be pretty hard to gauge how passionate someone really is about programming (do they love programming? Is it just a job? Do they even like programming? Or were they just told 'this is where the money is' so they became programmers without really caring about it one way or another?). One of the things I do is ask around about the current events surrounding the language / platform / tool involved in the position being applied for.
For example, if it's a Perl position, I may joke about "Hey, how about that Perl 6, been a decade huh?" If they laugh and they start joking that "Yeah, Perl 6 is the programming world's Duke Nukem Forever!", great! I may not agree that the comparison to vaporware is apt, but that tells me they actually know something about what's going on with the language, and that's a big neon sign for me that clues me in that this one probably is passionate about his work.
Another example, if it concerns MySQL or PostreSQL, I may ask a flame-war type question about "which is faster? which is more stable/reliable?" If the response is the generic school-boy crap, that tells me nothing. But if the response is something like "Traditionally, it's been MySQL that is faster, and Postgres the more stable, not to mention more feature-rich and enterprisey. However, since MySQL 5.x and Postgres 8.xx, they have gotten closer to each other in terms of feature and enterpriseyness and speed.", then that tells me this person is probably passionate about this whole web programming thing, because he's clued in to the developments of the tools he use.
I'm not asking you to read up on current events for the sake of reading up on them. This is something you probably are already doing because when you try to expand your knowledge and try to learn more about the language, the platform, the tools you use, you inevitably get wind of these current events, whether it's Perl 6 that never materialized, or MySQL finally getting enterprise features, or Postgres getting performance optimizations, or Rails exploding and people whining getting published all over the geek news sites.
4.)
Another thing that clues me in to how passionate a programmer someone really is is through his favorite programming / computer science books. Before, this was mostly "real" books, but more and more the answers I've received have become "e-books" or other online resources, even programming blogs (+1 for Raymond Chen). It's all good. I myself love e-books and online goodies.
Commonly, I just bluntly ask "What are your favorite programming books?" and "What book are you currently reading?" and "If not books, maybe online resources, or programming blogs?"
The answers I get from the good candidates are varied - "Code Complete", "Programming Pearls", "Mythical Man-Month", "Getting Real (37 Signals)", "jQuery: Novice to Ninja", to name a few of the titles that have often come up... and some boring college textbooks sprinkled along the way, too. I have read most of these books myself, so I try to make sure the applicant is not just spewing out BS by actually talking about the titles we both know about. When the titles are all foreign to me (I can't have read all the books ever made, of course), I may ask him about it and condense the topic for me. I usually write it down and try to see if the book is in the library or available online (google books for free viewing) and see if he actually did read that book and was not just stringing me along.
Most of the time, nobody bothered to BS me by citing a book he never read before in his life. Most of the disappointments here are answers such as "well, I'm not really a book-person". I just don't know how I can trust someone who is not into reading books (even e-books) or programming blogs or anything else.
That's about all I can say (talk about tl;dr), and I hope some of those help you out, OP. If you managed to read through at least some of them, give me a cool story, bro