Containers for decks of small cards?
You can get little plastic boxes in all kinds of shapes and sizes.

http://www.reallyusefulproducts.co.uk/uk/html/onlineshop/fullrange_rub.php

Also the little clear plastic bags with press-in tops (known as zip-lock)

http://www.ziploc.com/Products/Pages/default.aspx?products=all

For storage of multiple card-based games there are all kinds of small craft storage units with drawers of varying sizes. Personally I use the bags for games with lots of elements such as Agricola, and just keep all the bags of pieces/cards in the Agricola box.

Magic: the Gathering fat-pack boxes are excellent for storing multiple cards in (I have a friend who stores Race for the Galaxy, Gloom, The Great Del Mutay, and some regular playing cards in one) You can get empty ones from ebay or M:tG stores such as Troll and Toad (I'm limited to 2 hyperlinks).