I just had to waste the rest of your day with this: http://acorn.xara.hosting/wpmap/.

In the top box (Placeholder: Wikipedia), type a word, phrase or collection of both using the Enter key to separate them. Then press the Go button.
Start off with something simple like "tree" > Go.

A blue circle can then be single-clicked when it turns yellow to find related Wikipedia pages. each blue circle can be clicked again.
Double-click them to open a new Tab showing the clicked Wikipedia page.
Some circles are mono-pages or no-pages and so all you can do is see what Wikipedia suggests.

The file for all this is:
IFRAME - Wikipedia Page Visualiser.xar

All I have done is made a page with an IFRAME to the original.
I added some JavaScript to detect an IE browser and shout about it.

Enjoy!
Acorn