HelpACTUALLY hacking minecraft SMP

Sometimes i see people hacking minecraft... they arent mods or admins.. they are default. But they are still somehow enchant hacking and Spawning Items and even iConomy Hacks.... I just really wanted to know how to do that because i have looked into it but no results.. Can anyone help?

Can you provide an video of these hacks?

I meant the spawning hack that he was talking about.

It's not possible to hack server-side data. Just because you see someone as default doesn't mean they aren't an operator.
There are "exploits" where memory values stored in data are altered and for some time, a duping exploit and such will occur.

These type of hacks are not possible anymore.Everything is done server sided now.So if they did spawn items you would not see them b/c they are fake