Идем на
http://packages.ubuntu.com/, забиваем в поиск HEX и находим...
Package beav
dapper (editors): binary editor and viewer [universe]
Package ghex
dapper (gnome): GNOME Hex editor for files [universe]
Package hexcurse
dapper (utils): A ncurses-based hex editor with many features [universe]
Package hexedit
dapper (editors): view and edit files in hexadecimal or in ASCII [universe]
Package ht
dapper (devel): Viewer/editor/analyser (mostly) for executables [universe]
Package khexedit
dapper (utils): KDE hex editor [universe]
Package ncurses-hexedit
dapper (editors): Edit files/disks in hex, ASCII and EBCDIC [universe]
Package vche
dapper (editors): Virtual Console Hex Editor [universe]
Хватит?