Sometimes I pretty much know what assembly I want and it's much easier to make a C compiler produce it than to get GHC to produce it.
One example is multiplication in the complex roman numeral system vs. (our) simple arabic numeral system.
Another example is PHP (tool) for webapps (task). Worked for YouTube and CDBaby. -- Honestly, I think the concept of embedding commands in HTML is brilliantly simple, because the program is largely isomorphic to the result, making it intuitive to reason about. [disclaimer not a webapp developer]
Simple until you have to come in and maintain it. There are many levels of simple. What is often simple for the original writer is horrible for the person who picks it up later on and has to extend and maintain it.