Good Hex Editor

Every once in a while, I need a hex editor to poke at a file. There are a lot of editors out there, and a lot of chaff among them. I have a few requirements for what constitutes a good hex editor:

• Free - I don't use hex editors enough to justify a $40 editor.
• GUI
  
• Unicode capabilities
• byte-level editing
• Cursor tracking between hex and text frames
• hex and ASCII/Unicode text searches
• File comparison - what has changed?

I found one that covers most of these requirements, plus a few more neato features. If you haven't checked out XVI32, give it a try. I particularly like the wildcard search and replace function.

The only thing I would like to see is a file comparison feature. It helps in hacking another program: save a copy of some program's data, then make a change through the program and compare with the reference file. There may be a way to do this through the scripting interface (another neat feature), but it would be nice to see that in the application.