The Best Roadmapping Tool

People frequently ask me what the very best roadmapping tool is. While I use a number of tools in my day-to-day work, I find that "old faithful" always turns out to be the lowly 3x5 index card.

I use cards of different colors to represent different types of roadmapping concepts -- green for products/services, yellow for features/capabilities, etc. The cards are used in every step of roadmap development. For example, the priority ranking of each feature/capability gets written directly on the card at the end of the prioritization workshop. I typically keep the cards on one wall of my office while they are not actively being used in a workshop -- this lets people come by and add new cards or add comments/notes to existing ones. Here is what the wall looked like on my last project:

Finally, index cards are cheap!

I am thinking of creating a simple/inexpensive roadmapping tool for iPad and would like your feedback as to the features you would like to see in it -- just post a comment if you can think of anything.