What is the most interesting tag cloud implementation that you know? I'm searching for something easy to work with but somewhat non-standard. I know of WP-Cumulus 3D tag cloud, I'm interested in an interesting implementation - not necessarily in visual terms (as an example, a semantic grouping tag cloud can also be interesting).
Form over Function disease!
The tag cloud concept is to show tags and their frequency, typically with proportional font size
The Cumulus 3D and similars are just special effects and do not show frequency very well, or at all!
Stick to the basics and your users will love you
Colour coding tags into groups is the simplest improvement without distorting the nominal function. Show the colour legend if possible
I personally also like colour intensity to indicate the recent usage of tags. A popular tag that has no recent posts will be in a large font size, but in a low colour intensity so that it fades away and looks less important. e.g.
Personally I don't like tag clouds. A sortable tag list make more sense, since you'll still get the same information, AND you'll be able to find anything you might be looking for. Preferably sortable by tag name as well as frequency.
The most interesting tag clouds are probably those by Jeff Clark.