Often, if several stakeholders or even customers/channels are involved in the idea creation process, similar requirements pop up and can be clustered and all addressed with a single, smart solution.
So a tool has not only the need to collect requirements and break them into sub-ideas. It also needs the ability to cluster several reqs. into a category or "mega-cluster" so it will be easy to see the "biggies" vs. the "clutter below"

The end roadmap which the tool produces should look great, ideally to the standard of a good marketing department so that it draws people in and encourages them to read it and critique it.

Per David Atkinson's comment on Centralize requirements in one place, "The tool needs to make it trivial to take snippets of data from multiple sources (emails, blogs, random web pages, free-form feedback from customers, survey answers) and save them to the requirement so I can easily access them at a later date. If I have to spend five minutes, or even one minute, to log each piece of data, the system has failed. It has to be just as easy as dragging an email from outlook to a folder, or dragging a web page URL from IE to a folder."

It often happens when designing software products or components, mock-ups (e.g. Balsamiq) help all parties better understand the requirements. Traditional requirement management tools are too much focussed on "written requirements" while one image or workflow can clarify a thousand words. Collaborators will more easily understand requirements.

Being able to capture feedback and approvals from key stakeholders within the tool would be outstandin

My dream solution would manage enough data, in one place, to support all the types of roadmaps, and provide the display options that can generate any type of roadmap on the fly, for example internal Product Roadmap, internal Technology Roadmap, internal Sales Roadmap, internal Marketing Roadmap, and external Market-Appropriate Roadmap. The goal here is to minimize the maintenance of graphics, and have the graphics generated from the data that has to be maintained anyway.

To be able to view ideas & workflow & be able to leave feedback & approvals using a mobile device. Key stakeholders can be difficult to get time from

State & workflows can be to rigid in a lot of tools. Enable the ability to completely configure how the work flow goes, & what the states are

The key to any tool that will be of use will be the ability to easily maintain and update all of the roadmap items - particularily the sub task issues. Allowing users to "build their own" dropdowns and selections (with the abillity to override) may be helpful. I've never really wireframed something out to do this - just resigned myself to excel spreadsheet hell, trying to manage the hundreds of items....

It should allow me to link a specific requirement with a specific persona(s), and the priority of the persona should factor in to the prioritization of the requirement

I need a way to track ideas that have been worked on and how they have been closed, when they have been closed as well as what was closed, how much was closed and what is left to do ?

It's hard to prioritize all the great ideas that come in from customers, salespeople, executives (and sometimes spouses). It would be great if there were a simple way to map features ideas to company goals to provide an objective way of ranking ideas.

Network Diagrams are a great way to visualize dependacies between requirements.

I need to be able to communicate the current roadmap to all stakeholders inside and outside the company so I have something to present and so that I am not constantly inundated with questions about it.

I'm forever reviewing commitments against schedules - I would like to be able to see stories in a Gantt format.