Plugin Required: Logging of ideas

I am looking for a plugin, and I am not sure what to search for, where it will provide the capability for visitors to the site to log ideas. The concept behind this is that there will be a front-end element where visitors can log their idea, which would include categorising the idea based on a set of pre-defined categories and various other criteria. The back-end would allow a process to take place whereby a set of individuals can manage the ideas.

it sounds similar to a ticketing system, however it would need to be adaptable enough to cater for an innovation process of sorts.