Jim Bumgardner at ONLamp.com - Design Tips for Building Tag Clouds:

"Tag clouds are only one, specific kind of weighted list. There are many kinds of mappings from visual features to underlying data that have not yet been exploited. How about trying some weighted lists that don't look like common tag clouds? For example, you could map font size to time, showing more recent tags in large sizes. Or, in a historical database, you could map font to decade or century, using progressively older- fashioned fonts for older data."