As of this writing, in just over an hour I'll be giving a talk in Second Life on the topic "Galaxies in Collision".
Second Life is an online virtual world. Basic accounts in Second Life are free. I regularly give these talks as a part of MICA, the Meta-Institution of Computational Astronomy. Most Saturday mornings at 10AM pacific time (17:00 UT if we're during Daylight Savings), MICA has a public outreach astronomy talk. (However, like many academic institutions, we tend to slow down and get spotty over the summer.)
This talk will be at the MICA Large Amphitheater.