I can specify custom page titles by editing menu options and editing Page Display -> Browser Page Title but how do I do this for blog articles which do not have individual menu options?
Took me a bit to realize what you were asking. This thread is I think what you're talking about:
one option is to override the output of the category items, but it might be easier to just us a plugin like this one:
Create a system menu linking to the items, with prefered page titles.
What version of J are you using Neil, and are you using the native J blog option or K2 or another variety of blog?