My site has some moderators without access to backend, and as defence from spammers or bad guys, I can propose only to delete "bad" comments. But I guess that in some cases these comments must be analysed by administrator.
So it is very good idea to unpublish comments and/or ban spammers from front-end. There must be corresponding buttons for this.
Also it is very useful to make IP address in comment as link to WHOIS server. As variant you may link to _ttp://http://whatismyip.com/tools/ip-address-lookup.asp