Plan-It Earth Designs in Oregon has some recommendations to improve drainage and move water in your garden (Via the Oregonian).
Here are a few of her pointers: 1. Excess water is not a problem if you can move it to someplace that won't cause trouble. Use it to create a lush bed for thirsty plants or build a bog garden. Keep in mind that a rain garden, to function properly, must have well-draining soil (not the case with heavy clay soil). Adding 2- to 4-inches each of compost and gravel can improve your situation. 2. Gravel paths, cry creek beds and bermed beds can help drain water away from a trouble area. 3. Add plants to wick up excess water. Plants like rushes (Juncus), sedges (Carex and redtwig dogwoods (Cornus sericea) are excellent for wet winter weather. Native plants that grow along the edges of streams and wetlands are also great choices. According to Whitworth, many wetland plants multiply readily from seed, making it an economical choice for adding a wet garden. (1st Image via Flickr member lovestruck94 licensed under Creative Commons; 2nd image via Flickr memberextensionhorticulture licensed under Creative Commons) Via the Oregonian.