By chance, I stumbled on a GREAT site from United Kingdom... TerraGenesis. This site is dedicated to share information regarding creating terrain for miniature wargaming. The site is not specific for Warhammer 40k, but for general wargaming. 

It contains LOTS of articles... all of them good, some better or more relevant than others. It have information on products and projects in progress. The community is friendly and active in a mind blowing large forum! For those of us that want to build terrain (someday), this is a great place to visit.

Here is a list of some of my personal choices on articles (in no particular order.) There are over 300 articles... visit the site! Many thanks to Andy (the site's webmaster) for his input and guidance.

•  Wall Mounted Folding Table: Nice article on how to create a Wall Mounted Folding Table (duh!). Very clear explanations and photos. Maybe this way we don't have to drag the table slab from the hallway! :P
• Wooden Crates: Simple, yet effective terrain. Very nice, specially for Necromunda and Mordheim!
• Photographing Terrain: A nice article on how to take good pictures of terrain. This can be complimentary to the article compilation on how to take pictures of miniatures.
• Vallejo Game Color Acrylics: Very complete critique of Vallejo paints... my personal favorites!
• Mould Making with RTV Silicone: A good tutorial on how to create silicone molds. From the experts to us (the noobs). Must read for anyone who wants to cast.
• Billboard: A nice guide to create a billboard for your terrain. You MUST see it... it is a commercial for Gatorade featuring a Tau Fire Warrior! Great stuff!
  
• Flock - From Sawdust: We will be asking someone for some saw dust!
• Barbed Wire: Simple, yet effective way to make barb wire.
• Czech Hedgehog Tank Traps: Well, you need a place to put all that barb wire!
• Modular Cave System: A master piece! Easy to make, perfect to give a twist to Tyranid terrain. One could even create 'tops' to cover the terrain and create a fog of war... YEAH BABY!
• Tyranid Reclamation Pool: GW's tutorial has NOTHING on this one! It is not only better explained and illustrated, but the end results are far better.
• How to light an LED: Learn how to put a light on your terrain or model.
• How to light several LEDs: I bet you can't have only one!

 Check out their articles section for more on boards (Mordheim, Necromunda, Fantasy), buildings, How-To's and more!