Now that it's getting to be "Antenna Weather," its time to consider getting some new wire up in the trees...
Here are some links which deal with two of my favorite 80 meter antennas: the Full-Wave loop and the Half-Wave End-Fed Inverted L.
N1SU posted an article on loops: http://n1su.com/loop.html
N4KC has a great article on his horizontal loop: http://www.donkeith.com/n4kc/article.php?p=12
End Fed Half Waves / Inverted L's:
HB9DSU' observations on the Inverted L: http://www.hb9dsu.com/miracle-dx-antenna/
For me, the last word in most antenna suppositions comes from W4RNL (SK). Google L.B. Cebik's article "My Five Favorite Backyard Wire Antennas." He discusses the successful deployment of Inverted L antennas in considerable detail. He also discusses dipoles and loops for good measure. In fact, many of the articles above cite W4RNL in some way or the other. http://www.cebik.com/radio.html will give you some background and a great place to start.