Hackman Suite is a programmer's toolkit--make no doubt about it. This set of useful utilities is of little to no use to the average business or home user, but if you're a programmer--especially one who has to work on very low level operations or deal with finding extremely bizarre bugs--this set of utilities may prove very useful.
As the name implies, $35 Hackman Suite is a set of tools. There is a hex editor, a disassembler, a calculator which does binary, octal, and hex, and more. The hex editor is sort of the "center" of the suite; all of the other tools can be launched from there.
The disassembler particularly impressed me, because it supports far more than the usual x86 code. Have a GameBoy ROM file you want to look at? How about a binary file for Apple II emulator? The disassembler will read 6502 code, Z-80 code, and more. While some of this "retro" stuff may be of interest only to hobbyists, programmers who have to look at driver software which runs on non-x86 hardware will also find this useful.
Last of all, the program is extensible via plugins. Some are included, such a file merger (append one file to another) and its opposite, the splitter.
If you know what a hex editor is for--and trust yourself to use it wisely--Hackman Suite is well worth checking out.
Note: In this demo version, the hex editor can work only with files; the paid version can edit RAM, disks, and flash. The free disassembler only speaks "Intel"; the paid version handles many other systems as well The price of Hackman Suite is 25 Euros. The price in U.S. dollars is $34, as reflected here.