Although it may not be the quickest way to find out alternative words, this certainly is an interesting way of looking up words - visualthesaurus.com

To push this further, it would be great to have more information available about these words when you click on them e.g. Variations of word, Word in context, Origin of the word, Evolution of the word, Translations of word. All of which open up as a sub cloud (maybe different colour or different level).

I think this design method would also work well with the synonyms within word processing software... I can see it nicely greying out the page content to then show a word cloud.

It would also be interesting if you had a search facility with an 3D word cloud similar to this, however having panels either side of the screen showing visual information about that word e.g. go to wolframalpha.com and type in ‘Brazil’. Once set up you could the personalise this for say Lawyers or Mechanics to then show the relevant info towards their field (buzz words included).