I'm getting really into the Orion's Arm verse. Hard(ish) transhumanist Science Fiction. Also occasionally hilarious, like this article on Bayesjutsu.

Minus, a webcomic about a girl with godlike powers.

It is probably most famous for this image:

A Show with Zefrank, "sequel" to The Show with Zefrank. Quick, semi-daily shots of inspiration and motivation, with a huge dose of entertainment, like a Jason Silva with a wider audience.

Highlights from this run so far: An Invocation for Beginnings, Special Effects, Robot Future (a quick rambling overview of the Singularity)

Geek and Sundry is a YouTube channel started by Felicia Day, Wil Wheaton, and others. This sort of belongs under television, but I thought I'd post it here. They've got several programs every week, including new episodes (And the old seasons) of The Guild, probably the most popular web series ever; a podcast that reviewed popular Sci-Fi/Fantasy books that's now turned into a YouTube program, Sword and Laser; Table Top, a show produced by Wil Wheaton that reviews indie (read: German) board games by playing them with mini-celebrities; motion comics from the largest indie American comic book and manga publisher, Dark Horse; and my personal favorite, The Flog, which is Felicia's weekly video blog, where she does everything from blacksmithing to chainsaws. Table Top, The Guild, and The Flog are all fairly comedic. Sword and Laser is mostly critical review/interviews with authors. Dark Horse comics are, I believe, dramatic, although I've only watched one.

Future shows that are under production include Learning Town, and Written By A Kid. I don't know much about Learning Town, but it seems to be some kind of educational, music show. Written By A Kid looks awesome though - they're going to take stories written by 5-year-olds and produce them into 5 or 10 minute shorts.