The Great Barrier Reef is one of the main tourist attractions of Australia, providing many people every year with coastal recreation. Also, the Great Barrier Reef provides a safe shipping lane for cargo ships, which is the life blood of the Australian economy. The Great Barrier Reef is also a good source of ecological protection from cyclones, it takes a good portion of the force from cyclones before it makes landfall. The reef is also a big source of seafood, although now it is more heavily regulated than before. The GBR provides many mining opportunities as well, that have already been well over-exploited. Currently, much oil extraction takes place in the Great Barrier Reef as well, although this has been curbed in recent years. Without the Great Barrier Reef, there would be heavy erosion of the coast by crashing waves and storms. 
Negative Human Influences on the Region
Rampant over-fishing, pollution of all kinds, and global warming are the main contributors to a decline of the Great Barrier Reef. Up to a fifth of the reef has been permanently destroyed, a quarter faces immediate danger and another quarter faces long-term collapse. These factors combined have a domino effect that affects all forms of life living on the reef, including the corals, which make up the reef.  The highest impact things that humans do are coral mining for lime production, collection of reef organisms, outright destructive fishing methods such as dynamite fishing, uncontrolled tourism activities, and oil extraction.  Besides this, runoff from human civilization in general and sediment erosion contribute to the damage of the coral reef, along with worldwide decline of all ecosystems due to global warming. 
Picture of scuba divers at header: http://www.iscvid2011.com/images/uploads/snorkel_cairns_greeen_island_great_barrier_reef.jpg
 Moberg, Fredrik, and Carl Folke. "Ecological Goods and Services of Coral Reef Ecosystems." Ecological Goods and Services of Coral Reef Ecosystems. A Natural Resources Management, Department of Systems Ecology, Stockholm Uni6ersity, S-106 91 Stockholm, Sweden B Beijer International Institute of Ecological Economics, Royal Swedish Academy of Sciences, P.O. Box 50005, S-104 05 Stockholm, Sweden, (1999). Web. 11 Oct. 2011. <http://www.fishdept.sabah.gov.my/pubdocs/coralreef-evaluation.pdf>.
 "Human Impact on the Great Barrier Reef: Introduction." University of Michigan. Web. 11 Oct. 2011. <http://sitemaker.umich.edu/gc2sec7labgroup3/introduction>.
Picture of cooked fish: http://www.bbcgoodfood.com/recipes/4374/images/4374_MEDIUM.jpg
Picture of cargo ship: http://nauticalmind.com/blog/wp-content/uploads/2011/02/cargo_ship-3.jpg