I'm just wondering if anybody here knows where I can get some 2x2x4 pieces ... It seems that Lego doesn't make many just standard bricks that are 4 high ... I've found a few singles here and there on Ebay, but these don't exit in the pick a brick store and they are reeeally hard to find. Looking for about 16 Dark Stone Gray 2x2x4 pieces ... any leads? Or any idea why they don't make standard bricks that are 4 high? I assume it's because you can easily stack to 2 highs, but for cosmetic reasons I can't do this in my build. Thanks!
Another option you might want to consider is looking at 1x2x2 DUPLO pieces. They correspond to 4x2x4 lego pieces (slightly bigger than you are asking for, but not knowing the details of your build you might be able to incorporate these) and they interconnect (a 2x2 lego piece fits on a single DUPLO stud.) If you mount them sideways you get a 2x4 surface (but it would be 4 deep, not 2 deep as you requested). EDIT: This post shows how DUPLO and LEGO play together :)
As odd Todd mentioned LEGO never made 2x2x4 pieces. The largest brick of similar size is 2x2x3 and 2x4x3. For larger smooth surfaces LEGO usually uses panels. You can find all the panels LEGO ever made here: http://www.bricklink.com/catalogList.asp?catType=P&catString=91