I use hex editors a lot. In particular, I use XVI32 a lot. While it's a very nice hex editor, I feel that some extra functionality in many areas would be very nice. For example:

As such, I'm writing my own hex editor, HexEditIX, the first development screenshot of which is shown below. (of course, it's not much of an editor yet, but that's software development for you - you have to start somewhere)