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 сказал(-а) 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.