This is 10,000 short of where I wanted to be by now, but it's getting up there. easalle is officially ahead of me, but I'll see if I can't change that by getting some serious writing in. Not that I know where I'm going, mind you, just that it's somewhere in thattaway type direction.
I was going to go out and buy lettuce, but the Pitch Black that I had at work hit hard before I got a chance to, so I'm home and about to crash hard.
Before I do that, though, some thoughts:
I am extremely, perhaps excessively, fond of the narrative style that has one or more characters recapitulating insane, improbable, and/or hilarious events that you really had to Be There For to another character or group of characters who was/were actually not There For It. When the scene would take up too much room, or we wouldn't have our viewpoint character with a reason to be there (or we couldn't leave the "camera" there), I like to use that method. I especially like it in order to get extra laughs from a situation that, described real-time, might take too much of my notional effects budget. (I have an unspoken convention that only the action situations that in some way are important to the plot, the ticking away of K'tepi's "clock", should get onscreen effects time.) I also use this in place of flashbacks when I can.
I have a few favorite variations on the narrative exposition of humor. The one that I used for Harriet's Last Stand is a nice, simple one: I have one witness, and one interrogator. The witness lays the scene out in broad chunks, and the interrogator occasionally prompts, or interrupts, and keeps the narrative flowing. The interrogator's questions can echo the reader's probable questions (the reader wasn't there either), and can ask some of the questions that have to be answered in order for a comedic situation to work (without elaborate visual setup), and can keep an unreliable witness somewhat more honest, or keep a rambling witness on the track. (Lois McMaster Bujold uses this to nice effect in A Civil Campaign, where Armsman Pym tells Ekaterin and Team Koudelka about the events that transpired in Vorkosigan House after the notable dinner party. Left to himself, Pym would ramble; with people asking questions of him, he stays nicely on track of the topic.)
There's the Twin Effect, where two people who were both in a situation together, or share an idea, alternate sentences rapid-fire, each building off the other's exposition equally. The reader's attention is zinged about like a ping-pong ball, and what would be a less-interesting chunk of text in one character's voice is chopped up into information-age-size sound-bytes. J.K. Rowling has Fred and George use this (a bit too much); I have Beatrice and Sarah tell Sally about the Chocolate Situation in this way. Unless you have the voices of the two characters either extremely similar, or firmly distinct, however, overuse of this can lead to a muddling of the characters in the mind of the reader.
Another one of my favorites is the Reality Check. This requires two or more witnesses to a situation, and an audience. The role of the audience is relatively small in this; their presence, and reaction, is all that's really required. The primary narrator of this exposition is most often the person most involved in the action; they tell their story in a straightforward manner, yet with all kinds of spin on it to make them seem as if they were the reasonable person utterly in the right, or at least acting somewhat more sanely. They are left with the larger portion of the action to relate. The second witness is the Reality Check, and when the primary actor's story drifts too far from what actually happened, the Reality Check butts in with a clearer glance at the true wackiness. In my infamous "Kamikaze Fruit Fly" sequence, Dave tells a fairly straightforward story of a lab accident involving blue oatmeal, fragile glass, and escaped genetic experiments. His classmates Jeff and Scott interrupt him with the more embarrassing details that Dave might not have mentioned himself. In the Reality Check scenario, the traditional roles of straight man and goofy one are reversed -- the one who's acting wacky is the one who tries to tell the story as straight and unfunny as possible, minimizing the indignity, and the one who was actually acting sane in the situation points out as many as possible of the fall guy's failings.
I can and do write live-action humor, but the timing is a lot more tricky there, especially for a situation that unfolds slowly. It's a lot more interesting to hear about a character spending a few hours buck-naked on a rooftop after the fact, unless it's a major plot point that deserves stretching out live over several hours. I find it very "cheating" to write "Several hours later, he was still sitting there, staring at the sunset sky, waiting for the alien mothership to arrive," when I'm not going to do very much more with that character. Someone who was there, though, can summarize the important stuff for someone who wasn't.
I like humor.