Comment spam

I'm getting quite a lot of comment spam at the moment. Mainly for diet pills, male pattern baldness cures and online casinos, none of which I really need. OK so my hairline is receding but I own a fine selection of hats. I'm using enetation comments at the moment which allows me to delete comments and block by IP address. The problem is that deleting a large amount of spam is very labour intensive and they shift IP addresses so I can't block them for long. So, what are you doing about comment spam? A move to Typepad has been suggested, I'm told that you can block comments by URL, but I quite like Blogger. An easy answer for me would be to switch to Blogger comments. Does anyone use it? If so, can you filter/block/bulk delete spam comments?