Welcome to Gaia! ::

I'm surprised no one has linked something like these yet.

The NonVerbal Thesaurus -- An excellent resource for adding elements of nonverbal communication into dialogue.
Guide to Writing Advanced Internal Conflict -- An excellent resource if you're trying to put good internal conflict into your story or give your character a good internal conflict.
Female Behavior for FICTION -- Good for writing convincing female characters (though this one is more of a generalized tutorial).
Advanced Character Creation -- Another guide on character creation that gives a good idea of how to set up a very well-rounded character.

There are several more in Ookami-Kasumi's Writing Tips and Tricks tutorials in case you want to check them out. I, at the very least find them helpful (and hope you guys do too).

Here's a guild that's really been helpful to me. biggrin ((Though I haven't joined yet. But it's really good!))

School for Better Roleplaying

Here's another, though it's not a guild, just a roleplaying guide. A really awesome one, mind you.

The Really Awesome Roleplaying Guide. Period.