One person who read the packet post passed along Demetri Martin's 2001 Writing Submission for “Late Night with Conan O'Brien” (PDF).
It's overflowing with funny ideas and he does a great job at matching the tone/voice of the show. Martin wound up as a sketch writer for the show and, in 2004, wrote this series for Slate on what that was like.
On the monologue side of things: Josh Comers, now a writer for Conan, started out writing monologue-ish jokes at his blog Jokes That Won't Matter Tomorrow. Josh hasn't updated it for a while but it's still worth a look if you're interested in getting into that area.
And over at The AV Club, John Mulaney discusses the difference between writing for the SNL audience and his standup audience.
In terms of stand-up, I still want things to be clear to the audience. I’m more comfortable with things in stand-up, because I get to take the responsibility for them, and the audience knows who it’s coming from, vs. you’re putting it in a sketch with actors. Sometimes your point of view comes across best when you’re saying it, vs. injecting your point of view into a scene where maybe that’s not what the audience likes. So yeah, you can be more direct. You get to do a lot more in sketch comedy, which is awesome. You can be silly, you can be clever, things can be more absurdist. Those things can be in stand-up as well. If you’re a conversational comic, like I think I am, you also have to sell it to an audience rather than just talking about it. Like, having a point.
There’s this comic named Ross Bennett who I knew from the Comedy Cellar. I was doing this club called the Stress Factory in New Jersey, and I had bombed terribly. Ross was there, and he said, “You’re very funny.” I said, “Thank you.” But he said, “These people have no time for your cleverness. You need to get to the point.” I think there’s a lot of truth to that. You will really capture someone’s attention if you’re saying something that they find interesting, or agree with. Or they at least understand what you’re saying, and what your point is. You can be clever with puns and do whatever the fuck you want, but to have a point that at least you believe in, that’s a strong thing. That’s the backbone of stand-up.