I've written a short blurb on my other site QASEC.com on why using fuzzers in QA can pay off. This is a new site focused on speaking to the various people involved in a development cycle using a language that they are familiar with in short to the point articles.
"Fuzzers are used to perform negative testing against application inputs to identify unexpected behaviors. This is accomplished by throwing valid and invalid data in application inputs. Fuzzers can be good tools to identify filtering problems (E.g. a email address verifier that does a poor job) and after initial setup require little maintenance with the exception of medium to major application changes. These behaviors may be harmless bugs, but could lead to some sort of security risk. "
Article Link: http://www.qasec.com/cycle/usingfuzzers.shtml