I own the following, in (I think) chronological order:
-Wii Sports (obviously)
-Legend of Zelda: Twilight Princess
-Excite Truck
-Metroid Prime 3: Corruption
-Pokemon Battle Revolution
-Super Mario Galaxy
-Guitar Hero III
-Super Smash Bros. Brawl
-Mario Kart Wii
-Animal Crossing: City Folk
-Rock Band 2
-Guitar Hero: World Tour (only played it once, though)
-The Conduit
-Resident Evil 4: Wii Edition
-Metroid Prime Trilogy
-New Super Mario Bros. Wii
...so that totals 16 games. I also have some other games on my external hard drive, but I officially own copies of the games on that list.