It would be really cool I think if you did mitosis. Being the science wiz I am I am personally astounded by all of the different steps of this process in plant and animal cells and I think that you would be too. As far as a website goes I would check answers.com. I find that website to be very helpful and valuable in any of my research. A word of caution DON’T use wikipedia. The reason being anyone can edit it and it can sound correct but most of the time it’s not. If you want a more general search engine google, ask, and dogpile all work well and you will get thousands of results on this topic. I hope I helped you.

I’m not sure exactly what you are looking for, but here are some ideas:

-Genetic Diseases, maybe a particular disease such as hemophilia (where a person cannot stop bleeding) / you could put pictures of the disease on the poster board along with some grpahs or something.

-the Structure of a Cell, you can talk about the different parts of a cell, including the differences between plant and animal cells / For the poster you could draw the cells and label the parts and color it in.

-Mitosis or meiosis, these are processes cells go through to reproduce. / You could draw each step of the process.

-Classification of organisms, you could talk about the different forms of classification and display them on the poster.