What was meant by that sentance is things like the Cysid graphics, etc. However if you read further ... .
You further agree to grant to HALOGEN STUDIOS a non-exclusive, royalty-free, worldwide, perpetual license, with the right to sublicense, to reproduce, transmit, distribute, create any derivative works of, publicly use or display any materials or other information (including, but not limited to, ideas, concepts or techniques for new or improved services and products) you publish to the Web site by any means or by any media now known or hereafter developed
But you're right, it's not very clear in that regard. You own the copyright of any material you post on this site. By posting it on this site, you are saying we can do whatever we want with it. For example, if we decide to print a book of stories on the site, we would not have to pay you any royaltees or even ask if we could publish it.
However, since you are the owner, if you decide to publish your story in a book, you do not need to ask us any permission or give any royalty.
Make sense?