Can I change an application's listed category in the Finder?
The answer is posted here:

http://hints.macworld.com/article.php?story=20111017134102735


  To add or modify a category, you have to open the application bundle
  ('Show Package Contents', the under the folder Contents open the file
  'Info.plist'). 
  
  You then can change the existing category by changing the key called
  'LSApplicationCategoryType' (or create the category by adding a child
  named accordingly).


A list of possible categories is listed here:

http://developer.apple.com/library/mac/#releasenotes/General/SubmittingToMacAppStore/_index.html%23//apple_ref/doc/uid/TP40010572-CH16-SW8