Zentralblatt-MATH
MathSciNet has been listed above, but I didn't see Zentralblatt-Math. It does much the same thing as MathSciNet, although it has in fact been doing it far longer. Most papers get reviewed on both databases, and this redundancy if often very useful (although people frquently argue about whether or not we really need both nowadays - there have been many long discussions about this in various places).
Unfortunately, many students these days seem not to be aware of Zentralblatt. It is definitely a useful resource and if your institution pays for a subscription then it is certainly worth knowing about it and using it.