How to manage what you need to work on

I get a lot of suggestions and a few bug reports. Over the past year
or two I've tried a number of things to manage what I need to do for
each app. I've tried spreadsheets in Google Docs, simple bullet lists
for each app, Google Tasks from within Gmail, and paper lists.

Inevitably the master document grows a little stale, or it's too
difficult to remember which item was the *really* important item.

My latest solution is to write my development to-dos in the source
code itself in a way that prevents the app from compiling. Now when I
switch to a new project and open Xcode I get a list of errors. I can
view the list of things I need to do and get to work. There's
essentially no way to start working on the project without being
reminded of what needs to be done first.