Whenever we need to expand (a+b)[itex]^{n}[/itex], application of the binomial theorem means we don't have to multiply a bunch of binomial expressions together. Kids nowadays take for granted having a symbolic algebra program like Mathematica or Maple, but in the olden days, the B.T. could save a lot of time doing algebra (and be more accurate to boot, avoiding a lot of mistakes which might otherwise go undetected). The binomial coefficients are also the same as the entries in Pascal's triangle, and there is a simple algorithm which allows one to calculate these entries by using the first two rows of the triangle.
http://en.wikipedia.org/wiki/Pascal's_triangle