Free: Contests & Raffles.
Swanny, I ask people regularly to use their photos. Here is my take: Yes, a person can ask for compensation, however to get your name out there with some good photography you may want to consider giving the photos for free. Just add a stipulation that the photos must be credited each and every time they are reproduced and cannot be sold.
I have let publications, and currently several scientific texts use my photos just for the photo credit. It depends if you like gratification getting your photo published or if you are greedy and want cash. Most of the time if you ask for compensation they will say no thanks. Remember they can get lots of photos from agencies for not very much. Enjoy the publication.