FOSS gamedev and creative worlds

There is a new server being created!
I have a few questions for my sever:

1. What mods are good for servers?
2. What mods are good for anti greifing?
That's all I have for now, but thanks for the input!

(I did say I was making a mod, it's in the process.)

Sorry, this will have to be pushed up a few weeks, trying to sort out router problems. (The port forwarding is all in Chinese!)