Here are some tutorials I have posted on my blog over the years. They all assume that you know the basics of tatting already. Many of these tutorials show different ways to add "special effects" to your tatting; others just show ways to make things a little easier.
Working with Doubled Threads-- I'm not sure if this really rises to the level of a tutorial, but it does have a useful tip on working with two threads wound on the shuttle together.
Zig Zag Chains and Lock Stitch Chains
Finishing with SSSR to Hide Ends
Daisy Picots and Maltese Rings
Math for Tatters-- How to ensure that your edging will fit the fabric you're attaching it to
Loop Tatted Rings-- How to make them, and some examples of how they can be used
Adding Thread to the Shuttle-- But the giveaway described in this post is over. Sorry.
Joining Below the Current Tatting-- When to use lock joins, Catherine wheel joins, and slope and roll joins
I hope you find these tutorials useful! Please e-mail me if you have questions about any of them, or about tatting in general.