Last week, I purchased Mario Kart 7 with my Gamestop gift cards, and that left me with ~$8, so I decided to invest my money in two high-quality GameCube titles.
My first title was Star Wars Rogue Squadron II: Rogue Leader, a release title for the GameCube and a sequel for the first title on the N64. It's a very fun game with simple controls, but making sure the objectives are completed without failure is quite hard to do.
The second title I got was Geist. Geist was a FPS published by Nintendo about a person who tries to go to get some information from a company suspected of creating biological weapons that are being sold to terrorists. However, he ends up getting captured and having his spirit torn from his body, leaving him as a ghost who can possess objects/people. It's a really fun game with good ideas, but it feels too linear/forced since people must be frightened in order to possess them, and they must be frightened in certain ways.
I now have only $0.97 on my GameStop giftcard, so I'm guessing I could use it to pay off sales tax on my next purchase.