Bandwidth Limit Exceeded

My blog was down for some hours because bandwidth limit (3 GB) exceeded. I need to spend sometime to figure out why 3-4 GB of bandwidth being consumed? I don't blog often, most of the posts are in text and only a few example files are there.

Is it spammers hitting or some kind of DDOS attack?

AWStats and Google Analytics didn't help me much. I generally look at raw-logs in using VIM or one of my local-flex-app. Idea: Wouldn't it be good idea to have an Apollo app that can show server logs in realtime? 

I would appreciate if you have any suggestions on how to figure out the details?