iOS: If you want to play cards but don't have a deck, a free app called Card Table can do the trick. You require an iPhone or iPad touch and iPad to use it, but if you've got all that you just need people to play.
Card Table works by using your iPad as the table that everyone sees and placing the cards, themselves, on your iPhone (or iPod touch). You can then move cards from your iPhone to other phones or to the iPad. Basically, the iPhone acts as your hand and the iPad as a communal playing surface.
The obvious downside is that you need an iPad and another iDevice to get any use out of this app, plus you need other people with iDevices to join in. When a deck of cards can cost less than a dollar, nobody is going to go out and buy phones and tablets to play the game.
That said, while the app doesn't work as a replacement for the deck of cards you already have, it does work well for the one you don't. If you know you're around friends with iPhones and need a deck of cards for a game night, now you have one free of charge with the gadgets you already own. Plus, you never have to worry about shuffling properly.
Card Table (Free) [iTunes App Store]