Laura - The lemon may burn your plants because of the acid. Some people even use a pickling vinegar to kill unwanted weeds.
EDIT: Look here: http://wellnessmama.com/2565/homemade-natural-bug-spray-recipes-that-work/ I think this may be for skin sprays.
Here is one for gardens: http://www.comfycountrycreations.com/bugspray.htm
http://www.homegrowntexas.com/issues/NovDec03/
I'm gonna take a look at these! From the information I got, it was a mixture of just crushed up lemon and lots of water. There wasn't any damage to the plants from what I understood. At the very least, I think I can use it around and between the beds. Mint is also such a good repellent that it may be all I need. There is a rare mint from Florida that is said to be the strongest repellent.
So...essentially, I'm making an unsweetened mojito for my plants. And if some white rum finds its way into the mix, well, my plants will be really, really happy.