Kathy Sierra, a prominent technology blogger, is considering never posting on her blog again because of the severity of threats she’s received online.

Sierra has been the target of anonymous death threats for the past several weeks, according to the last post on her blog, Creating Passionate Users. The blog is for people “passionate about the brain and metacognition, most especially — how the brain works and how to exploit it for better learning and memory.”

In her latest post, dated Monday, Sierra included graphic written and photographic threats she has endured, as well as her feelings about the threats. “For the last four weeks, I’ve been getting death threat comments on this blog,” she writes. “But that’s not what pushed me over the edge. What finally did it was some disturbing threats of violence and sex posted on two other blogs … blogs authored and/or owned by a group that includes prominent bloggers.”

Sierra added that she’s cancelled all her upcoming speaking engagements. “I am afraid to leave my yard. I will never feel the same. I will never be the same.” She called on other bloggers to help her combat such “threats or even suggestions of violence” online. “Do not put these people on a pedestal,” she warns. “Do not let them get away with calling this ‘social commentary,’ ‘protected speech,’ or simply ‘criticism.’” Sierra ends the post with, “I have no idea if I’ll ever post again. I suspect I will. But for now, I have a lot to rethink.”

An article yesterday by the BBC said police are investigating the threats.

Most bloggers are furiously posting messages of support for Sierra, including Robert Scoble, author of the blog Scobleizer. “We’re putting ourselves out there in ways very few people do,” he writes. “We should be safe from death threats and other sexual attacks and stuff, especially from other bloggers. I’m going to stop blogging in support of Kathy, who I consider a friend and someone whose voice would be dearly missed here. I’ll be back [next] Monday.”

Scobleizer also turned off the function on his blog that allows people to post anonymously, according to the BBC. That tactic brings freedom of speech issues into question, but is certainly worth debating given the often-ugly nature of blog comments.

Roy Eappen of Dr. Roy’s Thoughts says he’s noticed that anonymous posters tend to be more vicious than those who identify themselves. “I will seriously have to consider whether I should continue allowing anonymous comments,” he writes. “Even free speech has some limits!”

Carla Schroder, a blogger on the O’Reilly Network, thinks the blogosphere has been tolerant of anonymous threats for too long. “Hey, what about enforcing standards and creating an atmosphere that permits actual useful conversation, instead of allowing vandals to run the show?” she asks.

But not everyone is so quick to quash free speech. “The blogosphere is built on the capability of ‘free speech’ (whatever that means) and offers us all the potential to have a voice,” writes blogger justonething. “If we start to censor the messages, surely we end up back at the mainstream media stage? Don’t we? We don’t want a blog governing body.”

A minority of bloggers, apparently a thick-skinned lot, thinks Sierra is simply overreacting. “Try this,” Mike Power sarcastically writes on his blog. “Host a party at your house. Advertise it widely. Let any shitbag who wants to come in. Result? One trashed home. No surprises there then.” He added, “What is this obsession with comments anyway?”

On his blog, Badrinath Srinath says he thinks Sierra made the wrong choice by surrendering to “some morons.” He passively adds, “I want to tell her ‘Come on, Kathy. That’s what people do.’”