I love Conan O'brien and I always thought one of the main reasons he started turning his show around was when Andy Richter left.
Granted, the show was already doing better when Andy was there, but I think the show became so much better with Conan doing his back and forth with Max Weinberg and Max's deadface response and lack of talent, which became and awesome joke. Also Conan then used the entire band in many different recurring jokes(La Bamba being gay for instance) and the announcer Joel Goddard(always joking that he was in love with mid 20's Asian Males).
Conan's writers oviously had a huge role with all their awesome skits, but Conan himself became so much stronger without Andy holding him down. Random stuff would always happen on the show and Conan would be able to use it to his hilarious advantage(The duck that ate it's own shit unexpectedly for example).
I watched the first of Conan on the Tonight Show and Andy's stupid laugh was constantly in the background, sounding so fake, and being so annoying, and actually ruining quality jokes.
Andy's own career has gone nowwhere. Everything he's been on has been a gigantic failure(Minus his cameo role on Arrested Development), and the only reason he's around at all is because he's been best friends with Conan.
I hope that Andy eventually leaves the show and goes to Jimmy Fallon where he can help stinkup that show.