* when someone comments on my blog site it is sent as "pending" => This is already present in the Q2A core, in the admin/spam section, along with many other options
* limits the number of registered users coming from the same IP address => This is already present in the Q2A core, in the admin/spam section, along with many other options
The only thing is not present is the bulk delete, which would save some clicks but will not decrease the amount of spam registration attempts