Solitaire is one of the enduring classics of computer gaming, keeping all the skill and entertainment of the real thing and ditching all the shuffling and laying out. Full Deck Solitaire is fantastic free solitaire game available from the Mac App Store.
Full Deck comes with 22 "deliciously delightful" solitaire games wrapped into one tight little package. You've got the old favorites like Klondike, Spider solitaire and Pyramid, combined with the less common likes of Thieves of Egypt and Tri Peaks solitaire -- there's something for almost everyone.
The card movements are all well animated, with appropriate optional sound effects, and you've even got the option of an animated "video background" of the sea lapping up on the shore on a moonlit night. You can of course use your own background image if the stock green ones don't do it for you. You also have three decks to choose from antique, clean and large print, or if you hate all of them, you can define your own card backs from an image of your choice. You have three choices of card size too, meaning you can just about customise the whole card playing area to your liking, including playing full screen on Lion.
Each game has a nice load of statistics, that tell you how many games you failed to win, at least in my case, and of course there's a full set of rules available should you have never played a particular game before.
So, if you're looking for a decent solitaire game for your Mac on the cheap, you can't get much cheaper and better than the free Full Deck Solitaire.