There is a very important bug in newest version of Essentials on bukkit dev. It allows player to copy their money with no limits, so Essentials became not useable on my server.
How to copy money:
"You have to create new account, it MUST be with smaller letters, like test1. Enter to the game and transfer money, for example 1000$ to test1. Then, quit game and join on Test1 (Do not join on nick with bigger letter first, because it will not work). And BUM! You have 1000$! Transfer it to main account, and go back to test1 (with small letter). You still have 1000$ here and you can transfer 1000$ again to your main account. Congratulations, you have duplicated 1000$! Remember, join first on nick with smaller letters, then with bigger, or it will not work."
Tested, it works. Probably because Essentials is cloning file without deleting file that was before, so money is duplicated (on 2 UUIDs).
Please, fix this.
32 GB RAM DDR3
Intel Xeon 3.2 GHz x4 (8 threads)
3x SSD 120GB
Debian Wheezy 7 OS