Spam & Abusive messages
Banning IP number doesn't work, i used to have another big service a couple years back which had massive attraction to spammers. At that service i banned all anonymous proxies, i even wrote code for detecting proxies, but it is fighting against something you can't win, they even hack home computers to send spam to web services. So if you ban 1000 ip's the spammers will find another 10.000 proxies to send spam through.
I know there's a facility where you can see the IP address of the person who posts a message.
However can something be done to block the IP addresses of individuals who do these things on blogs, I have another blog where I keep getting bombarded with offensive messages, along with spam and child porn links. I know as traffic increases in my thumblogger blogs these things will reappear.
It's a real problem for the whole internet. I advise you to enable the option "Moderate" > "Only comments of non registered users" (only registered users can post comments, comments posted by anonymous users require your authorisation) or even "All comments" (all posted comments require your authorisation).
If you also enable option "Send a email to me when someone posts a comment" you will also receive a email when someone posts a comment.
There are anti spam measurements in thumblogger, like not allowing posting x comments in x seconds.