I've always believed that systems are *more* valuable as they get older because they have more games, and those games are available more cheaply. Sadly, some of the games are harder to find.
Nevertheless, I'm looking to make a list of PS2 games to get my grubby hands on. My girl loves Frequency and has not yet played Amplitude. I'm borrowing those from a friend since we couldn't find them for sale in town.
If there are any absolutely must have games, the very best PS2 games, and they're available on ebay or at used stores, make the list. I already have God of War and Hot Shots Golf 4.
[edit] Since there is such a large pool of games to choose from, I'm interested to know if they support wide screen and surround sound. Also, if anyone has had any luck with wireless controllers let me know which one you have -- we have to sit about 10' from our screen since it is very large, and a wireless controller would be awesome.