Our leaders in this session are PalMD and Abel Pharmboy. I hope that these comments on this topic will be useful, as I have never blogged anonymously or under a pseudonym, but we are blessed with many such folks at this conference, and I will focus on the experiences they share in this session.
Important points: If you're concerned about your safety or that of your family (as many in the room reported abusive comments, threats, and more in the line of blogging), keeping pictures out is a good idea.
Some of the reasons that people do write under pseudonyms tell us why: someone going on the job market who did not want her writings to determine what hiring committees would think of her, someone whose employer has no positive opinion or use for blogging and considers it a distraction at best, someone new to blogging who considered using a pseudonym just a standard part of the world of blogging, to write under a persona that is very different from that of the author and may be difficult to bring out under one's real name (the so-called "kick ass alter ego"), and others who work somewhere with particularly sensitive information (trade secrets, military technology, etc.) that don't want to be entangled with being "outed" as an employee of Cogswell Cogs even if their blog has nothing to do with their work. Clearly the range of reasons for not blogging under one's real name are varied.
One audience member raised the question of whether authority is compromised by not being transparent about your identity. Are authors of blogs given less authority if they will not identify themselves? This is clearly a sensitive issue within science, but PalMD wants to ensure that we don't conflate transparency with honesty, because many pseudonymous bloggers strive to ensure that they are being honest and open about their work and the topics they write about. There are many ways to do this, including ensuring you use proper references if blogging about your discipline or your research, building over months and years a devoted readership that gains trust in your writing, and establishing a relationship within a network of bloggers that can vouch for the accuracy of your blog material even if they do not know who you are.
"Putting the genie back into the bottle": Is it possible to become a pseudonymous blogger when you are already using your real name? Some in the room have done it, obviously by moving to a new platform or otherwise dissociating from your existing blog that has your name stamped on it. To get creative, it's possible to change some of the details that readers might use to identify you; if you're not identifying your co-worker anyway, make him a her. If you're not saying who employs you anyway, say that it is a medium-sized research university in the Midwest even if it's a small liberal arts college in the South. And so on. If you are writing about similar topics that you covered as a named blogger, there can still be problems with keeping your identity from being revealed, so watch out if that is a concern for you.