You can find the C128 games at Arnold http://arnold.c64.org
(Arnold may be a bit hard to access, try anyway) and some games (freeware/public domain) can be found at Funet: http://www.funet.fi/pub/cbm/
Oh, no one mentioned these: there are a few good games that run in the C128's 80 column mode including a very nice Solitare game and a pretty good Space Invaders clone. I believe they may be found on Funet.
Forgot to mention - the Elite 128 can be found at Funet too. It runs in the C64 mode but uses some coding tricks to get the game to run at 2MHZ.
Proud to be "predictably pedantic".
"Business is war, I don't believe in compromising. I believe in winning." - Jack Tramiel
"Frammin' on the jim-jam, frippin at the krotz." - The Wizard of Id