This talk will concern "irregular singular" type problems from differential equations. Such problems involve, characteristically, formal power series solutions which diverge everywhere. Some re-summation methods will be discussed for such problems, with the goal of achieving representations (called Borel approximants) for actual solutions, which converge relatively quickly and also in large regions of the complex plane. A general convergence theorem for Borel approximants will be discussed along with some applications to several different kinds of irregular singular problems.