You actually don't need separate emails for this. You can use (name+tag@provider.com, Gmail supports it and others too I'm sure). Or you can use your own domain

You actually don't need separate emails for this. You can use (name+tag@provider.com, Gmail supports it and others too I'm sure). Or you can use your own domain (Google Apps makes this really trivial) and have the part before @ be the sitename (that's what OP suggests) and then have catch-all address. You might receive slightly more spam if you turn on catch-all, but I have a setup like this a it works.