Zuma - PC Game
One of my son's friends tried out this game on my computer one day (through MSN), so I downloaded the "free" copy. Next thing I knew, I'd used up all my free Zuma time. I had to buy it!
Since then, I've been playing Zuma whenever I feel like zoning out (formally reserved for TV watching).
Zuma is a combination of Tetris, Space Invaders, Galaga, and a few others. Lots of fun. Very addictive.