Spammers Unwanted Again

Well, seems a few resourceful folks are still getting by my spam filter. Not sure if they are real people solving the Captcha or something automated. My guess is that it is real people. I'm seeing only a couple of posts on random articles causing me to go hunt down and delete the offending stuff. I don't get many comments, but I don't want to completely shut down the service like I did in the past. If it really is people, they'll just join and post anyway. I thought about turning on or adding a comment approval routine. Just not sure it is worth it. Any other bloggers out there with this problem and what did you do about it?