I recently came across a blog post on a very popular topic in software development:
Technical Debt 101 by Maiz Lulkin
Most of the developers I know (myself included) would be the first to advise for a re-write of a legacy application. Likewise, most of the managers that I've worked with are always there to advise against it. They would say things along the lines of "This would take too long, we need this new feature yesterday" or "We don't have the funds or resources to support this right now".
While both sides have valid points (and are probably exaggerating their points for their own cause) the truth lies somewhere in the intersection of both circles in a venn diagram. This article - in my opinion - gives a description of what the venn diagram looks like. Maiz paints a detailed picture of what both sides argue and then goes on to explain what that intersection area contains. After reading his post, my doubts or uncertainness about re-writes have been silenced. A required reading for developers and managers alike.