If you've never heard of stevia, it's a sweet herb used as a sugar alternative. In fact, it's been highly-touted as a better sweetener because of its negligible effect on blood glucose (in stark contrast to the usual high-carb, high-calorie cubes you drop on your morning coffee). Now, you can scratch off sugar from the shopping list with Grow Your Own Sweet Leaf, a DIY kit with everything you need to start a stevia garden.
From what I've read, you're supposed to get the sweetener out of the plant through a drying and water extraction process. Which sucks a bit because that means more work than just taking a bag of sugar home from the grocery. To its credit, growing stevia sounds simpler than planting a sugar cane farm in your backyard. Maybe you can try picking a leaf and just dipping it in your coffee (note: at your own risk)?
The Grow Your Own Sweet Leaf kit comes with its own terrarium (which doubles as the packaging), measuring 5.6 x 3 x 6 inches. Stevia seeds, gravel, planting mixture and stake are all included, along with a background card and an instruction sheet (so you'll actually know what to do).
I've never taken stevia, so I have no idea how it tastes compared to sugar. It's 300 times sweeter than sugar, though, which means some ridiculous amount of taste bud magic awaits (provided you can figure out what to do after the plant has grown). Thinkgeek has the kit available now, priced at $14.99.