We've shown you a few automated irrigation systems, both large and small, but if you're an Arduino fan, you'll love DIYer Jouni's set-up, made out of a bucket, a submersible pump, and plastic hose.
It may not use water recycled from your air conditioner, but this compact self-watering solution is perfect for any size garden. It's extremely simple, too (apart from the Arduino, perhaps), and doesn't require a lot of complicated building plans as far as the hose and pump go. And, not only will the Arduino water the soil when it starts to get too dry, but it will even tweet about it so you can make sure everything's on schedule (and so you know when you need to refill the bucket). If you don't have the room for a giant vegetable garden or a full-fledged drip irrigation system, it's a great set-up for your apartment or basement tomato patch. Hit the link for more information, and let us know your favorite self-watering garden tips in the comments.