Let me preface this with the fact that I've never presented a poster at a conference. Lots of papers, but no poster. I should probably do something about that... but I find it much easier to write a talk than to prepare a poster. That said, I did prepare an information poster for work that I *really* liked and got good feedback for, so perhaps all is not lost. I -did- spend several years working in graphics-y type jobs, including book layout, copy design, and at newspapers, and I think picked up a few things along the way.
And you know, it's not a bad thing to have to force myself to think about data differently -- i.e. how to present it largely visually as a poster vs. as a narrative. Hmm.
But posters aren't just posters anymore; they're going multimedia!
Bone Girl recently posted about putting QR codes on conference posters. As a poster-maker, you go to a website (here's an example) and tell it what information you want encoded, and it feeds you a QR code that you then put somewhere on your poster. Poster-goers then snap a picture of the code (it looks like a bunch of pixels) with their smart phones and have access to whatever data is linked. It can be a digital version of the poster, poster author contact information, more detailed background, reference list... you name it. It's a great idea, especially for poster-goers who don't have time to read your poster right there and then, or who come by when you're not there, or who are notorious at losing business cards, or for things no-one has thought about yet.
QR codes are cool, and can be put to good use. But please don't forget not everyone has a smart phone, no matter how adamantly the phone companies want you to believe it's true!
I particularly liked the link Bone Girl posted to Better Posters, a whole blog targeted to the academic crowd (by an academic). The blog contains very good general points (no more than 2 fonts, don't use comic-sans, etc.) and lots of nitty gritty (columns, color theory, poster critiques, fonts and more fonts, poster software reviews, etc.). I particularly liked this graphic, from the Poster Venn post:
I disagree that no-one cares about references, though; or contact info. But the rest? Yeah, I see his point (though some funders require you to mention them whenever you present info they paid for).
Another website on creating good posters that leads by example: An Effective Poster
This site is much more of a how-to, from start to finish, than Better Posters. If you need to make a poster fast, I recommend Effective Poster because it will sequentially walk you through the steps. If you have some additional time, or want to improve a poster you've done, or are just interested in the process and considerations, then definitely pop over to Better Posters.