RDNA's forums have an excellent Poser 5 section with lots of shader tricks. Don't miss it!
Very busy, lots of smart folks around and a lot to learn. Exciting things are happening there, so don't miss it.
General Poser 5 tutorials
Curious Labs has a collection of basic tutorials to almost every room of Poser 5 on their web page.
3-Axis are selling a video called "Poser 5 demystified". I haven't seen it myself, but thought I'd share the link for those interested in it.
Fallencity.net has a collection of tutorials, including the famous series from Dr. Geep.
There are some useful Poser 5 tutorials on fignations.com, some on Poser 5 hair, one on how to use your Poser 4 library in Poser 5.
Renderosity has a tutorial section called "Poser 5 Secrets".
They have a section with links to various Poser 5 tutorials.
The web page of Jeremy Birn who wrote the book "Lighting & Rendering". Highly recommended! If there is one web page that I want every 3D artist to read and unterstand then it is his 3-point light tutorial.
Leigh van der Byl
This girl as some very good texturing tutorials you should read. Go there.
"Shader Node Magic" shows you how to improve the look of V3 in Poser 5 (works also for other figures).
Excellent hair room tutorials at the Studio Verite forums.
She has a mini-tutorial called "Creating Locks of Hair".
Perpetualvisions.com has a big tutorial on Poser 5 hair.
There is a tutorial on improving the skull cap on Walkerplanet.com.
Now here's a cool one: A tutorial on how to use Poser 5 hair to make a waterfall.
PhilC has written tutorials on the basics of the Poser 5 cloth room and on using Poser 4 clothing with the cloth room.
You can find a tutorial called "Making Posable Models in Poser5 or Poser4 Pro Pack" on 3DToday.