'Cold crash' is a home brewers term for a period of time at the end of the primary where the beer is put in a cold place to encourage the yeast to drop out of suspension, and may also work with freely distributed hops and any other suspended solids as well.
I usually dry hop with the first four days in the warm then move my FV into my unheated garage for two days. Some people use their fridges for this stage.
Be aware that if you have chucked the dry hops in as they are then most will have dropped to the bottom but there will still be some floating about, which will get transferred to the next stage when you siphon the beer out. Unless you are not bothered about hop bits in your beer (some aren't) you need to filter the hops out. I now use a nylon mesh sock that goes over the end of the siphon tube that works really well, like this
http://www.ebay.co.uk/itm/5-x-Home-...390902?hash=item35f5d12436:g:0ykAAOSwIwhWTF6w
Mine came from a Festival kit.
More on dry hopping here
http://www.thehomebrewforum.co.uk/showthread.php?t=61045