Sometimes I see boxes in web pages that contain links in different font sizes. The most-often visited links are in bigger fontsize, the "less important" links are in smaller font size. I would call this box the "weighted size link box", but google does not understand this.
I want to have a mediawiki extension for this box, so can you tell me how this box is named?
It is indeed called a Tag Cloud in web design or simple a Weighted List in graphic design. As mentionned above, avoid using them as they are often shown. they are unreadable. Ask yourself if you've often found something in this cloud. It should be called a tag fog.
The worst I have seen is a tag cloud in 3d moving with the mouse.. that's just... useless..
Instead of using this, try some alternative, Like using opacity & boldness on tags and order them from most important to less important.. after all, we're all used to read from Left to Right not from big to small.