informal portrait poses?

Perhaps this sounds familiar to many of you: as you become known as an enthusiastic amateur photog in your circle of friends, you are occasionally approached to take informal portraits. Or perhaps, like me, you have a few "real characters" in your life, and you'd like to take some informal shots that capture something of them.

Most of the time, I find myself working with:
- available light (rather than a studio set up or flashguns)
- one, or two lenses at most
- available patience, if you know what I mean

So, my question: can you suggest some general poses, angles, or other tips, that you can recommend, so that the short window of opportunity isn't frittered away?

here's one tip you likely won't find in any book or magazine article:

Set up your group shots with two angles in mind....

Build your shot...(when doing a group shot, start with one person, pose them, shoot then add another person, shoot, and so on. eg Wife, then Husband and wife, then husband wife and child).

ask the people who are waiting to be posed, to stay in one spot, right near where you're working. Make sure it has good light, and background.
You or your assistant can snap some "Candid" shots of the people that think they're waiting to be photographed.

These may be helpfull....

http://www.focusingonflorida.com/Documents/Benji_RulesOfPortraiture.pdf

http://www.vci.net/~mmorgan/pg2.pdf

Thanks to you both for the feedback!

Don, I had a wedding photographer tell me recently that she works in just the opposite way - starting with the largest group of people, so that the "wanderers" don't have to be repeatedly rounded up. But I like your approach of having a candid waiting area - I bet many of your gems have come from this time.

Brian, the links are indeed helpful - thanks!

One thing that I'm trying to do is to think about the characteristic gestures, expressions, environments, etc, of people I hope to photograph. Then when the opportunity presents itself, I am asking them to do something that they are already familiar/comfortable with, and hopefully end up with an image that really represents who they are.

Any further tips on informal and available light portraits?