For me, though my choices have been slim would be as follows.

1. Lost Winds - Just beautiful and enjoyed the story and gameplay

2. World of Goo - Amazing, simply Amazing

3. Toki Tori - Great game and pretty tough in the later levels, a real gem

Megaman 9

So far I've only bought Crystal Chronicles, but I enjoyed it a lot when I played it. It's a really addicting game once you get going, and it's the only game I've EVER bought downloadable content for (unless I did it for another game without realizing it).

I thought that might be up there (megaman 9).  I just never really got into Megaman, but the game sure does look like an awesome treatment to the fans.

I think it will be on a lot of people's lists. It's one of the best games you can get on any of the console stores. I'm thinking about buying it, but I haven't played too many Mega Man games in my life.

I've never played a megaman game before Megaman 9 and I'm enjoying it.

Only be sure to like "old style gameplay", this game is based on pattern/level memorization .

world of good - great.
lost winds - great.
mega man 9 - fun but frustrating
art styles cubello - fun and adictive
art styles orbient - fun but not great
gyrostarr - forgetable
strong bad 1 - sort of funny but not worth it.

Lost Winds and Toki Tori for me. Lost Winds is short, but it's a wonderful experience for the time spent.

Toki Tori is an excellent challenge, I have spent about 14 hours on it and not yet completed all the hard levels (much of that time is spent zoomed out trying to figure out the perfect route for each level, only to find when I try it that I missed an obstacle that is unpassable without going somewhere else first)

I probably like World of Goo the most. However, my friends and I like to play Wild West Guns and Midnight Pool every so often.

I so far have downloaded only 2.

Mega Man 9 - My first Mega Man game, and although it was a challenge, it was incredibly fun. The music was great too.

World of Goo - Just started the third chapter and it is amazing so far