Friendlier and more cutting edge than most academic sites, Ohio State University's WebGarden offers a wide range of multimedia resources. Expect a deep illustrated plant dictionary, with 1,200 entries, and a downloadable plant database for your handheld. Botany enthusiasts will appreciate the PlantFacts database, which searches for content from over 46 university and government sources. Not sure when to prune your roses? Try the sites FAQs, which has more than 800 gardening answers.

BEST: Collection of 200 short gardening how-to videos, ranging from tips on basic landscaping to lessons on growing tropical plants.

WORST: Poor navigation. Be prepared to hit the "back" button.