Even after that, my thirst was not satisfied, so I scrounged around my house for some material that would serve my needs. Pretty quickly I realized that old CD's were perfect for this project.
The Cd's weren't dangerous enough, so I made some out of metal.
You can go to Home Depot and cut your own out of some duct metal, they're quick and I don't really think they need another Instructable.
You can get "blank covers" in the electrical section in many stores. They are high quality aluminum disks that make GREAT shuriken. They sink into trees up to the center. (Poor tree! :P ) Seriously, if you weight one of those suckers, get a good throw in, they'll make that sweet *THOK* sound and stick a good inch or so in.
Yet Another Update:
Perhaps I should clarify a bit more what these "blank covers" are. They're round pieces of metal, maybe 4 or 5 inches in diameter. (I don't have any on hand to measure for sure). They are used as covers for electrical boxes. Apparently, what metal they're made out of varies from store to store.
At the local Wal Mart, I found "Electric Box Covers - Blank, Round" (3 dollars for 4 discs of galvanized steel). At Home Depot, they appeared to be made of aluminum, and were sold in packs of 2 for 4 dollars.
Personally, I'd buy the ones from Wal Mart. They're a bit weightier than their Home Depot cousins, and they cost a bit less as well.
Ah, here's phyco_ninja's Instructable on cutting out metal shuriken from electrical box covers. He uses a Dremel tool, rather than shears or tin snips to make his cuts. Note that he doesn't start out with a completely round piece of metal. It's perfectly fine to use box covers of that shape.
Again, no throwing pointy things at people / animals / property!