Personally, I liked both Fluxx! and Apples to Apples as a great card game, though I do recommend playing them with atleast 4+ people to get the full experience

Also, might I suggest the Chair Game? It's like a reverse Jenga, where you work to stack odd shaped chairs on top of each other, trying to eliminate your pool of chairs.

There is another card game that you could play in "solitaire" called Chrononauts. I've had some friends recommend this game, but I myself haven't played it.