+2  A: 
Jamie Dixon
How closely can it be customized to resemble Many Eyes? Particularly with colors and removal of chart-grid layout?
smazurov
Pretty much everything is customisable with these charts. We've tried out a lot of charts because our requirements mean we have to be able to change just about everything, including the type of chart at run time. The guys seem to be providing the best solution for those types of needs. Also, you can use these components in Flash or Flex and develop around them. They fully expose all the events necessary to both surounding components and Javascript in the page. You can customise the colours of the charts and also the way they're layed out. All in all, damn customisable. :)
Jamie Dixon
A: 
Eric Melski
A: 

You may use some physics library to create that in Flash... eg. disccollision, QuickBox2D(example)

Andy Li
These seem to be completely unlike what the OP is looking for.
Eric Melski
Not what I'm looking for, unfortunately
smazurov
+2  A: 

Flare is a good data visualization library for flash.

They have demos here - click on layouts->bubbles to see what you are after.

Reuben
A: 

The closest I could find is A Better Tag Cloud by Anson Parker. Its written in javascript and uses canvas for drawing the circles. Its not 100% ideal but was a great starting point:
example
Demo

smazurov