In my travels over the web I've discovered this site, which appears to be intended as a way for women to share their experiences of being sexually harrassed by strangers in public. The idea is to encourage the harrassees to "holler back" (hence the ghetto patois term, "hollaback") at the harrassers to embarrass them and discourage further harrassings.
The incidents recounted fall into the following categories:
1) Blatant egregious "that guy should be arrested" incidents. Examples--a guy grabs a woman on the subway, the serial subway kicker (not sure what weird thrill a guy gets out of kicking a stranger, but there you are), a guy on the Metro masturbating.
2) Inappropriate, potentially threatening behavior. Examples--a guy follows a woman down the street, making catcalls when she won't respond, a guy in a van (vans are the sine qua non for creeps! Especially minivans) wagging his tongue at a passerby, a man asking for sex on the subway after the woman already told him she doesn't want to give him the sex.
3) Cases where a guy uses a cheesy pickup line. Examples--"hey pretty momma, I just want to get next to you!", "you are dreamy!"
4) Cases where it seems like the woman complaining is sort of actually bragging about being hit on. Examples--"I was subjected to come-on lines from eight guys in one day, and I was only wearing sweat pants!", "Why do so many men have to hit on me, I totally don't like it! I must have walked down that block like six times, wearing only a potato sack, and still they ask me for a date".
Now, case 4 we can dismiss out of hand, clearly such postings are ego strokings for the writer. Case 3 isn't criminal, it's just a matter of a guy with absolutely no social skills trying whatever he thinks works. In such cases, the harrassee should probably feel sorry for the harrasser and suggest he come up with better pickups next time.
For case 2, it hits a gray area--yelling at, humiliating or mocking the harrasser will probably work most of the time, since it's likely that this is just some bully who gets off on fear and isn't used to someone making a scene at him. But then, what if he's a nutjob and it escalates? This is where it makes a difference whether a lot of witnesses are around. If not, it's probably best to keep your distance.
As for case 1? This is why they invented tasers.