For some crazy reason (uni) I thought I'd look at browsing and comparing text files using word clouds.

Browsing or searching a set of files for particular subject matter.
  1. User would be presented a word cloud of all the words in all the files.
  2. User then clicks on the word that relates to the subject there after.
  3. The set of files is then filtered to contain with the filter selected word.
  4. If there are still too many documents in the set repeat from step 1.
  5. Else the user can browse the remaining files.
Science collection
In this test collection of science documents filtered by the words "Species" and "Animals". Using this has some strengths and weaknesses. By browsing your exposed to terms that you might have forgotten, that will help the user to remember more about the subject. But key words relating to your target might not be frequent enough to be significant in the word cloud.

File comparison
Science collection
This works quite well.. sometimes. As with all word cloud stuff, you need to filter out words that dont signify any subject, like "the", but coming up with that list is difficult and subject dependent, its not just the most common words or anything. Luckily its working pretty well in that example.

for a LIVE DEMO! go here :)