While creating mods for Sid Meier's Pirates!, I found it very frustrating to try to make substantial changes to the game's executable using IDA Pro because the built-in assembler is very limited and can only assemble one instruction at a time, and if you make a mistake you may have to type the whole program again from scratch! Furthermore, the free hex editors for Windows tend to be buggy, and typing machine code into a hex editor is error-prone. So I created a basic assembly IDE to help me write mods and patch executables, called ExePatch. I didn't expect to release it, but I thought it might be helpful for others.
In lieu of a long text introduction, I'll just embed the tutorial video.
Download tutorial video: ExePatchTut.avi (15.1MB, but the YouTube video is better because I've corrected some errors via annotations.)