These are links I've found useful or interesting.
A useful forum for writers: Absolutewrite.com
The well-known market trackers and other useful things sites: Ralan.com and Duotrope.com
Of course there's the online critique group, Critters that is open to all writers of spec-fic.
A Clarion Writers' forum set up in 2009 is open to all alumni and current students of Clarion, Clarion West, and Clarion South, and to current and former Clarion (and CW and CS) instructors. You have to join to participate.I really like online speculative fiction magazines. They're mostly run by people who are excited about them, and perhaps because they tend to have low overheads, many of them are really innovative. (I estimate that the cost of running an online magazine is about 10% of the cost of a print magazine.) Many of them archive material (with the author's permission), so you can go back and browse. And of course, you can send links to people who you know would just love that story or poem or artwork. Many of them are free, supported by donations or grants.
This is an ongoing list, in no particular order, of some of the electronic spec-fic magazines.
FREE MAGAZINES
CLOSED MAGAZINES
Some of these are leaving their archives up, so the old stories are still available.
PAID SUBSCRIPTION MAGAZINES