I've been flying in Europe for some time now, I have never seen a student deal.
But, that does not mean you won't find a good deal. What I would do is, I would first look at scanner sites as given in earlier answers, and then look at the original website of the airline to compare prices.
Also, you may want to aim for nearby cities/countries, as the distances in Europe are fairly short, and inter-country transportation is smooth and affordable. Thus, you can aim for any of the German airports as well as Belgian, Dutch and Czech airports (You can of course aim any of the European airports, but these will be the closest ones). Then it would be trivial to reach Berlin by another flight / train / bus in a reasonable price. But still, don't get your hopes up with the student discount.