Wow! 540 hubs! I'm not a hubaholic yet (only been hubbing for a couple of weeks), but the feeling of satisfaction from writing something, getting it published instantly and then being able to watch visitor numbers grow through the stats is fantastic!
I think I might be on my way towards addiction. I do check in every day and I've always got ideas buzzing around in my head for my next hub. At the moment I'm just lacking confidence in getting on with it. Maybe I should just take a deep breath and aim at a hub a day?