Spambots and how to block them
I had a particular spammer that kept registering as a user on my site. I finally added a plugin, IP Blacklist.
When I logged in today, I saw 11 attempted hacks. They show up in red in the sidebar of admin. When I checked the IP address in google, they all came up as spam bots. The list give you the option to just click on Block IP, and it blacklists them for you.
Until today, I never new this was happening. The users I knew about, but not the bots.
I recommend this highly.