Ah! I LOVE packet tricks! What is more amazing that using just a very small amount of cards to produce a series of really cool effects? Lay people notice the difference, too. I've had more than one lay person comment that it's more amazing when I use a smaller amount of cards to do tricks. I think this is because lay people instinctually know that we can use a full deck to mask things. When you only use a handful of cards, there's nowhere to hide anything. Or so it seems!
I have created several packet tricks, some of them sold right here on Penguin Magic. I think they carry my effects "Twists and Turns" and "What It Isn't". Maybe a few others as well.
When it comes to justify pulling cards out of a wallet, many ways of doing this. First, if the trick uses a bunch of Jokers or a few blank cards, it makes total sense to pull them out of a wallet or envelope as you don't find more then two Jokers in a deck or blank cards.
But if you want to pull out normal cards from a wallet, just say that they are your "lucky cards" and then launch into your trick. As long as you have some minor justification, no one will question it.
A great one to carry around is John Bannon's "Spin Doctor". It's sold here on Penguin. Also, his booklet Tribolical, co-created by my buddy Liam Montier is an awesome booklet of three great packet effects that use a wonderful display called the Bullet Party Display. Definitely check it out. Awesome magic.
Peter Duffie and Aldo Colombini also create and sell amazing packet effects.