Both of these serve... Well, a crapton of people. We made up two of these and it lasted 2 days of epic parties and there were still about 2 gallons left (but we also made just one and it only lasted 1 night with 4 raging alcoholics)
Lemonadey-shit (Mixed in a 5 gallon sports drink cooler thing) - This is a variant on the "Hop Skip and Go Naked":
1) Pour in 15 cans Coors Light (Used as a slightly alcoholic filler water-like filler)
2) Pour in 1 entire handle of the shittiest vodka you can buy (We used Vladimir - again, this is used as a 3)highly alcoholic water-like filler)
4) Dump in 1 ENTIRE 19oz thing of Country Time lemonade powder
5) Wait for the head to go down and stir vigorously. If you haven't thought ahead and found a stirring implement big enough to use in the cooler, you may need to just man up and stick your entire arm in.
6) Crush a 12oz frozen concentrate limeade thing and throw it in. It'll probably sink and dissolve over the evening - but the tap on these coolers is at the bottom so it's all cool.
6) Drop in a bag of ice, stir vigorously to cool shit off.
7) Add any other white liquors (we've used white rum, gin, even more vodka, everclear) to taste, remembering to stir between tastings and fill. If you get in a bad spot, you can add more powder to back off the liquor taste, but we've never had a problem with it.
8) If your ice has melted, re-ice it now. Another whole bag will do.
It tastes, no shit, literally just like lemonade. The booze is barely detectable. Ours ended up filled to the 15L mark on the cooler.
Fruit-punchy-shit (Mixed in a 5 gallon sports drink cooler thing) - this is a variant on the "Jungle Juice":
1) Add a bag of ice to the empty cooler.
2) Pour in 256oz of red Hawaiian Punch (128oz bottles, we don't know the exact flavor but there can only be so many red ones... Right?)
3) Pour in 128oz of orange Hawaiian Punch (128oz bottle, again, we guessed at the flavor.)
4) Pour in two fifths of Bacardi 151 (don't forget to make jokes about the "Flammable Liquid" warnings on the label)
5) Stir (again, if you failed at planning you may need your entire arm), and taste because you actually have a viable (though not terribly alcoholic) beverage here. We, however, were not satisfied.
6) We added about half a fifth of (luscious branded, I think) Raspberry Liquer (it was what we had left)
8) At this point, it's probably still not very alcoholic. We've tried several options and they all worked well - we've done an extra bottle of 151, we've done various amounts of everclear, and we've also done vodka (cheap Vladimir crap works). Just go to taste and don't forget to stir. If you get backed into a corner, add more orange Hawaiian Punch.
9) At this point, you're going to have like no ice left whatsoever unless you refrigerated your ingredients ahead of time. Throw another bag of ice in.
It tastes like a cross between Hawaiian Punch and a Grateful Dead. Delicious. Again, you should end up somewhere around the 15L mark.
These are actually rather tasty, chick-compatible, rather inexpensive alternatives to a keg. and have been a standard since we stopped Epic Partying with glass bottles (we had some incidents). We figure one of each of these, plus a case or two of canned domestic is good for about 40 20-somethings for a hellza pool party, and has a staying power of about 2 days (just remember to stir and re-ice before reusing)
For general concocting and experimenting, we find that working in bulk allows WAY more freedom than working in a glass or two. One error (most commonly assuming that something can be made better by adding Jose Cuervo) in a small quantity situation will result in something that tastes a lot like... Well, we have a term for this particular phenomenon, and it's called "Jose Muerto". It's also a good idea to keep any and all gold tequilas (and also Jose Cuervo white) WELL AWAY from the experiment area, just in case they accidentally get added in bulk. Gold tequila ruins everything it touches and only belongs in shot glasses, as does Cuervo white. GOOD white tequilas can be used to excellent effect at times, however.