Instead of fretting over commercial posts, we all should take a cool approach to the problem. Whenever I see a message like "Make quick cash!", "Great Anti-Cellulite Cream!", "Don't be Lonely!", "Earn $50,000 a week!" or something along those lines, I forward the message to the postmaster where the message originated from, explaining why I find the post inappropriate or offensive. Chances are that the postmaster will look into the issue and have a talk with the abuser, if not go ahead and cancel his/her account altogether (has been known to happen).
If the offensive message originated at an academic institution, then I know I am going to get the sucker in a lot of trouble. Universities have strong policies about the misuse of their computer resources. It is likely that after receiving complaints, the offenders will lose their accounts, and in addition experience the wrath of some disciplinary committee.
So, for the good sake of the net, if you see a commercial message posted by idiot.morons.are.us, forward the message with a piece of your mind to postmaster.morons.are.us. You will be doing everyone a favor.
The same goes for trolls. Also, the right thing to do about trolls is to report, killfile, and forget. If you react to a troll on a newsgroup you are feeding it. If you ignore the troll it'll go back under its bridge sooner or later. Trolling: sending off-topic and/or inflammable messages to newsgroups and/or mailing lists. For example, posting anti-herbal messages to a herbal newsgroup.
A note on finding correct abuse addresses: I quite like http://www.spamcop.net
You'll find more hints on news:news.admin.net-abuse.* - these newsgroups are very flammable because they attract the wrath of the spammers they fight, but you will find information on how to fight spam, unwanted ads, unwanted binaries in non-binary newsgroups, and UCE (unsolicited commercial email). Have fun!