When is a tag cloud a good (or bad) choice for visualizing data?

I'm currently reading some academic papers on Google Scholar, but I'm interested in the personal experiences of developers and web designers - when do you and don't you use tag clouds instead of another visualization method?

From stackoverflow

• **Thirteen Blog Clichés**

• I personally find tag clouds that use different sizes of characters to represent tag counts a visual mess and a bit of a fad'ish approach. I prefer to see an ordered list with the most popular at the top (with a count next to each tag). But that's maybe just me.

  Patrick McElhaney : Tag clouds don't have to be messy. The one at http://delicious.com/tag, for example, is clean and functional.

  Kev : @Patrick - hmmm....still looks like a big wall of text, but not the worst I'll grant you that.

• In my opinion - always a bad thing.

  I hate the bloody things. Messy and unusable.

• Tag clouds are useful to show both what tags exist (in alphabetical order so it's easy to locate one) and the relative prominence of each tag.

  Personal experience: I used a tag cloud for the skills section of my resume.

  Thomas Owens : After I'm done with this internship, I'll be rewriting my resume...and I know what I'll be doing with the skills section. Thanks. :)

  Patrick McElhaney : My pleasure. :-) More information on the skills cloud here: http://stackoverflow.com/questions/5905/writing-a-good-resumecv#5931

  Triptych : I will be stealing this. Awesome.

• I would have to say that I not a big huge fan of tag clouds, I just think there are better was to layout tags then in this mess of words on the side of the page.