Spike Speak by ShadowKitten - How to write your Spike without making him sound like a working class Cockney. You mean he isn't? I hear you gasp. Then read this, it will certainly help.
Angelus Speak by ShadowKitten - As with the essay above, Shadow sorts out the ye's from the you's. Well worth a read.
Let's Just be Friends by Tania - Don't want them shagging? Then read this for a take on the two male vampires and their platonic relationship.
What's in a Name by Tania - A run down of the names of our favorite vamps over time.
Five Shadows: Writing the many incarnations of Angel/Darla by Tania - It does what it says on the tin.
Vampire Sex by Nan Dibble - A look at the dynamics and drive of vampire sex and sexuality.
A Few Thoughts on Historical Fanfiction by Peasant - An expert in the field shares her insights.
Going Old School by Tania - More insights.
Getting back to the Grindstone by Josey - And yet more insights.
Beta's Bible by Tania - Thinking of being/using a beta? Want to know what to expect/look for? Tania tells you.
Fanfic Terms by Tania - Just what is an AU or a WIP?
Tania's Timeline - Exhaustive list of who was where, when. Up to date as of 'Destiny' AtS season 5.
Resource Links - History, sexuality, language. Find your reference material here.