Level Layout Tool

[speakr]

Hello there.

I'm looking for some software to help with visualizing and mapping game levels, almost like a flowchart. This is for a text adventure, and I would like to be able to construct some sort of top-down image that I can look at while developing and know where the character is "physically" in the game and what is available (ie items, secrets, exits) to them.

It doesn't need to be complex. In all actuality, I could use Excel for this and just make cells represent the different areas of the game, but I was hoping there might be a more efficient program available. Does anybody even use anything like this? Or am I just a hopeless dreamer?

Oh, also preferably free and/or open source.