Here is another set of hiding spots for Call of Duty Modern Warfare 3.
Mission Hiding Spots
The Mission map (too small for ground war :), is very interesting map layout. There are 3 choke points. 2 low ground and 1 high ground. This video shows you a few cool spots to pick off people on either side of the map.
Underground Hiding Spots
Underground is a relatively hard map to find places to hide where you are in control of everything. There is usually 2+ ways to get to every section. Flanking happens quite a bit on this map. So this video has given you a couple nice spots at each side of the map to hide and get your kills.
Outpost Hiding Spots
This map is very campy as is, so there is not a huge portion of the video dedicated to Outpost. Yet, if you need a few more, check em out.