Have to say I was kinda surprised (in a good way) they dropped the Raj/Penny thing so quick, but on the other hand it was resolved pretty well in the first episode, so ...
Sheldon first going crazy about the chair and then finding a million different reasons to come running back to Penny to get rid of it was absolutly hilarious! Especially when Penny scared him of with the cushion and he came racing back to knock the third time
Of course not to forget Pennys door-opening-rhymes!
And how funny was Rajs and Howards online making out?!
Just the best!