When working on your research poster, start with these guidelines and judging criteria in mind. Those should guide your design decisions, based on the content you have to support them.
Here are some (of the many) helpful poster design resources available on the web:
Stanford -- "Posters and displays are specialized communications that demand careful planning and design to assure that your audience will understand your project and results."
Swarthmore College This site includes a poster gallery on Flickr and various other visual examples, plus numerous handy links. I also like the irreverent voice in which the author writes about the poster sharing process.
University of Buffalo site has many links and a straightforward explanation of the process.
The Cain Project, at Rice University, also is well done.
University of Kansas -- Outdated design and interface, but the information could be helpful.
University of Guelph -- A Canadian perspective.
Dartmouth -- A web presentation of a lecture on this topic.
Here is one recommended by the WSUV Research Showcase site, too, from Duke