I have a sealed bag of LEGO bricks that I am trying to identify. The bag is labelled with a large number 7. The pieces are dark blue, light gray, dark gray. It looks like there is a smaller bag of pieces within the larger bag. I took photos, but can't figure out how to add them to this post. Can anyone help me?
Without pictures it would be extremely hard to tell, especially since both dark and light gray are very common colors. However you might be able to identify some of the dark-blue color pieces to see which set the bag is from. Dark-blue is a much less common color than the grays, so it would be quicker to identify what you have. The fact that it is a #7 bag seems to indicate that it is coming from a larger set.
What I would do is look at the dark-blue pieces and find one that is NOT a common piece (so anything that is NOT a plate, tile or brick). Then go to the BrickLink color-guide for dark-blue pieces, and find the one you have. From there you will see which sets the part comes in. Identify another 3-5 less common pieces, and you should be able to see which set the bag is from. Here is the list to all the elements that come in dark-blue: http://www.bricklink.com/catalogList.asp?catType=P&colorPart=63&v=3