presentable Java features and programs

  A Java course participant asked me near the start of the
  beginner's course: ?What can one do with Java? Could you
  show me three Java programs??.

  Even though I am giving Java classes for a long time, I
  was not well-prepared for those questions!

  ?What can one do with Java?? - A possible answer might be:
  ?Write Java programs.?, but possibly not what he had in
  mind? What would you answer to a beginner? (He already
  knew VBA.) (Well, strictly, to write Java programs, you
  use an /editor/, Java [in the sense of ?the JLS?] then
  gives them meaning.)

  ?Could you show me three Java programs??. Well, I already
  showed them the java compiler ?javac? and the hello-world
  program at this point. But maybe these were not the programs
  he had in mind? At least, they might not be representative
  (in at least two senses of the word). What programs would
  you choose to show?

  In the end, when I am to show a Java program, I always show
  JDiskReport, because it can be started easily and fast via
  Web Start and is a really useful application, and one can
  choose the L&F at runtime.

  Do you know any other Java applications that could be shown
  in such a case, preferably applications that might be famous
  and/or impressive and/or where one can immediately see that
  they are useful and/or fun (and/or that can be downloaded
  easily )and possibly (in the case of software that can be
  used for free) shown/started easily?