homo, queer, and fag immediately pop to mind

The bunch of gays you know must be pretty different to the bunch of gays I know, FB. If someone shouted at them "You're a homo/queer/fag/poof/queen" they'd almost definitely ignore the tone of voice and say "Yes. So?" or - more often - they'd respond with something more witty. "You're just a disgusting old queer" would be met with "Take that back - I'm only 25. Every birthday."

I'd find it quite hard to come up with a term that my gay friends would find genuinely offensive, in fact - unless it was in the realms of "child-rapist" or whatever, which is something else entirely.

Dunno, I live quite close to Brighton, which has a significant gay population, so my experiences may not be representative. And then the English (can't really speak for the whole UK) attitude to gays, which is coloured by a long-standing appreciation of theatrical camp, may make a difference.