I've just started to hit the 10Gb limit and at the moment traffic is increasing at around 1 to 1.5Gb per month.
My server runs APC to cache as much as it can. I have known threats blocked via firewall but do not want to do country based IP blocks. I dont appear to have anyone scraping my site and hotlinking is prevented so there is no leaching there.
Talking on forums always gets the "you get charged for international bandwidth???" response from most people and they go on to suggest caching and CDN's like cloudflare, clearly not understanding that the result would be 100% international traffic. I even tried this recently for proof of concept and the caching does not make up for the domestic traffic being transformed to international.
So me question is really, what options do I have? Any way to reduce international traffic without making the site suffer? I'm currently serving 1million hits per month. Traffic is 53% domestic 47% international