What are some GUI applications that will let me view and edit binary files (executables, images, etc.).
If you're using KDE, Okteta is the way to go.
sudo apt-get install ghex
From the app's Github page:
GHex is a hex editor for the GNOME desktop.
GHex can load raw data from binary files and display them for editing in the traditional hex editor view. The display is split in two columns, with hexadecimal values in one column and the ASCII representation in the other. A useful tool for working with raw data.
sublime is a good choice and it is multi purpose editor.