The end of episode 8, when Derek shows his trailer to Meredith and tells her facts about him. Then they hold each other's hands :) I think it's the only moment from season one where they look really happy :D
I liked it when Meredith found out he was her boss and they talked and she dicho to him "stop looking at me like that!" ... "Like you've seen me naked" hehehe that was funny and he had the biggest grin on his face.