I used this tool, albeit briefly, maybe a year ago. Now, I can't for the life of me remember what it was called.
First, it was an online/web based tool, not something you download. Everything was set up using a grid. Not like a combat grid, mind you.
It was like... each square in the grid was like its own mini tabletop/folder, which could be filled with notes, monster/item/power cards, etc. You would have a square for your town/city, one for the exterior of your dungeon, and one square for each encounter.
You could navigate between the grid squares quickly, making it easy to check the name of an NPC or update notes.
You could also sign into your DDI account and it would let you pull pre-populated monsters/items from there. It was definitely designed for 4e, but you could probably use it with other editions or even other games.
To top it off, it had a pretty nice/slick web interface. It LOOKED good.
So, what is the name of this application? I can tell you it is NOT: