Just discovered a brilliant feature in OS X Console app: hashtags. A little button in the lower left of the window opens a panel that allows you to filter messages by process name or by “tags”, where the latter stand for simple hashtags like those in Twitter.
Ticking checkboxes on hashtags will restrict display to messages containing either of them:
Have each log message tagged with something like subsystem name or importance, and you will be able to quickly filter output by any of those aspects.
Here is the code that produced the messages above:
NSLog(@"Database initialized. #debug #database");
NSLog(@"Fetching data. #database");