Natural solutions to garden problems are always my favorite, especially if they're cheap and easy. Crushing egg shells at the base of my plants is one of my favorite ways to deter slugs and deer, although some studies say it doesn't work on slugs after all. Just make sure you rinse them well, otherwise you'll attract rodents!
I've always loved having ladybugs in my garden. They eat aphids at a voracious rate--about 50 a day--so if you have a bunch of them you'll keep your garden free of aphid pests! There are lots of bugs you can use in your garden, though, like lacewings, which also eat aphids, mites and other insects that do garden damage.
Which helpful bugs do you like to keep around for your garden's health? Which other natural remedies do you use in your garden?