Here's another excellent post by Matthias Noback.

Reuse-in-the-small is definitely possible. Reuse-in-the-large is deemed to be impossible, because no two problems/projects are alike, but practice proves otherwise. There are reusable components covering entire subdomains, which are nonetheless quite successful. The chance of success is bigger if such a reusable component is used to cover for a generic subdomain. Using an off-the-shelf solution in such a case helps you save development effort which can instead be redirected to the core domain.