Truly Portable Apps

There's a lot of talk about "portable apps" these days. Portable apps being programs that you can run off of a USB keychain drive. However, most of what I've seen are Windows apps that you can run directly from your USB key chain drive. What about the truly portable apps? The ones that will run on any computer- Windows, Linux, or Mac OS X? Right now, the only apps I know of that do this are Java based, so here's my list of truly portable apps:

• jGnash
  jGnash is a personal finance mananger. It's completely free and will run on any computer that has a Java virtual machine version 1.4.0 or greater.
  
  
• Thinking Rock
  Thinking Rock is a free software application for collecting and processing your thoughts following the GTD methodology.
  
  
• Risk
  Wow! This implementation of Risk in Java is amazing. In fact, this is the nicest looking Java app I think I've ever seen.
  
  
• Java Sudoku
  Just like the name sounds, a Java based version of Sudoku. Needs JRE 1.5.0 or above.
  
  
• Secure Data Manager
  Secure Data Manager keeps your passwords stored in an ecrypted file. Requires JRE 1.4.1 or later.
  
  
• Java Shishen
  Shishen is a Mahjonng tile removing game. The tiles are not stacked as they are in most Mahjonng variations that I'm familiar with. Instead, you can only remove 2 tiles if it only takes 3 straight lines (or less) connected by 90 degree turns to get from one tile to the next. The idea is to to remove the tiles in the least amount of time possible.
  
  
• jEdit
  jEdit is a mature programmer's text editor with hundreds (counting the time developing plugins) of person-years of development behind it.
  
  
• jBidWatcher
  A Java-based application allowing you to monitor auctions you're not part of, submit bids, snipe (bid at the last moment), and otherwise track your auction-site experience. It includes adult-auction management, MANY currencies (pound, dollar (US, Canada, Australian, and New Taiwanese) and euro, presently), drag-and-drop of auction URLs, an original, unique and powerful 'multisniping' feature, a relatively nice UI, and is known to work cleanly under Linux, Windows, Solaris, and MacOSX from the same binary.
  
  
• yEd
  yEd is a graph/diagram editor. It can be used to generate drawings and to apply automatic layouts to a range of different diagrams and networks. It is available as a free download with no restrictions on its functionality.
  
  
• Freemind
  Freemind is mind mapping software. It's great for laying out a bunch of interconnected ideas. A great example of just how smooth and polished a Java desktop app can be.