This is actually new to me, not sharing, researching and practicing on-line, but doing so with my writing and actively seeking out other writers or resources there. I have yet to settle on any favourite sites, and prefer at this point to explore.
I am still married to books, magazines, articles and face-to-face encounters with other writers as my primary source of information, prompts, cross-feedback and sharing.
I am the current leader of The Write Group, http://bit.ly/writegroup, and have been busy building our online presence for our members. So essentially, I am building our own sites from which we can connect with others. These sites our's connect to will be the ones we will frequent. It is my hope the list will be ever growing.
Having said all that, I have seen some exceptionally creative writers' sites and look forward to a time when I too have such a site for fellow writers and fans to communicate with me through.