hexedit 1.2.12-4 (armhf binary) in ubuntu precise

 hexedit shows a file both in ASCII and in hexadecimal.
 The file can be a device as the file is not whole read.
 You can modify the file and search through it.
 You have also copy&paste and save to file functions.
 Truncating or appending to the file.
 Modifications are shown in bold.