During the winter I keep a bowl of TrueLemon packets on my kitchen counter, but in the summer I'm a huge fan of fresh lemonade. I put a dab of honey in it for flavor, but for the main sweetener I use Splenda. A couple of summers ago, I experimented with flavor variations and came up with several that keep me from getting tired of Just Plain Lemons when it's hot enough to drink two pitchers a day:

1. Raspberry -- puree a couple handfuls of fresh or frozen raspberries and add to a pitcher of lemonade.

2. Ginger -- slice, grate, or chop an inch or two of fresh ginger (exact amount calculated according to your taste for spiciness) and steep it in boiled water for half an hour. Subsitute it for the equal amount of water in your lemonade pitcher and the juice of 3-4 lemons and enough Splenda to sweeten. Or just add a splash of ginger water to a glass of your previously prepared lemonade. 

3. Lavender -- this one is a little more fussy, but not much. Steep a handful of fresh lavender sprigs in two cups of boiling water for about ten minutes (Definitely do not steep it much longer or the taste turns bitter. I actually use a french coffee press for this so that you can just push down the handle and pour the water off the top, leaving the bits of lavender behind.) Pour the hot lavender water (with the flowers strained out!) into a large pitcher.  (If your diet allows for a bit of sugar, you may like to stir a couple tablespoons of honey into the hot water for flavor, making sure it melts and dissolves while the water is hot.) Add the juice of 3-4 lemons, depending on how sour you want it, fill up the pitcher with cold water and ice, and then mix in packets of Splenda until you've got it to the right degree of sweetness. This one definitely requires fresh lemons to complement the fresh lavender taste, which is spectacular! (Not everyone likes the lavender flavor, but if you're a fan of Earl Grey tea, you'll probably enjoy this.)