*There might be some spoilers for people who haven't seen season 3...you've been warned
*
About Izzie cutting Denny's LVAD wire...I agree with you that in real life, she probably wouldn't be allowed to return. But this is Grey's we're talking about...and Katherine Heigl is one of the main characters, so we just KNOW that she would. I don't think that even if Izzie kept the 8.7 million dollars, she would've spend it. She had a really hard time to even deposit the check at the bank...i can't imagine her just quitting her job and just living on those 8.7 millions dollars. I'm glad she later helped pay $300,000 for that girl's surgery and later on spend everything for Denny Duquette's Memorial Free Clinic (LOL...the clinic that got build in 8 days!)
I really really hope these two will last. We all know that they'll end up together, no matter what. Shonda herself has said that she started the series with Meredith/Derek and that she will end the series with Meredith/Derek. I was disappointed with Meredith in the season finale though.
Addison and Mark wasn't a one night stand. Remember, Addison later on told Derek that she and Mark lived together in NYC for 2 months after Derek left for Seattle. Addison was even pregnant with Mark's child! I was proud of Mark though when he ended it with Addison and said that he broke the 60 days promise even though it was Addison who broke it. He FINALLY realized that she didn't want to be with him. I wonder who they're gonna pair him up with next season...