1) Got a neighbor that's a real pain in the ass? Do they have a lawn? Do they have a garden that's accessible? Yes to all the above? Great! Go out and get yourself some grass-killer and fill the suckers hose with the stuff. Then sit back and wait for them water their lawn! Nuff said?
2) Does the person that you want to get even with drink red wine? If so, have I got one for you! Get yourself some Neutral Red, a water soluble, crystalline, red dye. Mix some into the persons wine and wait for them to take a leak. (Nuetral Red comes out as red as it goes in, and people have a tendancy to get really nervous when they start pissing what they think is blood!
3) (I'm surprised nobody mentioned this one yet.) Go to a pet shop and buy a fancy looking pet collar and leash. Then, the next time you see a dead animal in the road, attach the leash and collar setup to its neck. Attach the whole thing to revengees rear bumper, making sure to toss dead animal under the car so it won't be seen. When revengee drives away, chances are he/she will be stopped by either a cop or a member of some animal lovers group for draggin some poor defenseless pet down the road. Either way, they are gonna have some awful quick explaining to do!
4) Last, but certainly not least, is a great stink bomb. This one takes a bit of time for preparation, so it's not too good for spontaneous revenge. (But it's worth the time!) Get a quart jar with a rubber seal. (Mason jars work quite well.) Pour about 1/4 to 1/2 inch of crystal Drano along with about an inch or so of warm water into the jar. Place the lid on the jar and allow the mixture to sit in a warm place for about an hour. Take the lid off and add six egg whites, (no yokes). Add a quarter cup of Methylene Blue, then fill the jar to within an inch of the top with water. Seal the jar tightly and allow to sit for four to six weeks. (I warned you it takes a while!) When the 'bomb' is ready to use, you can either throw it like a molitov(sp?) cocktail, or shake it up and pour the contents out, making damn sure you don't get any on yourself. The results have to be seen, or is that smelled, to be beleived!