Recently I've tried out the Thaumcraft 3 mod, and I'm very impressed.
The mod centers around using various items to research new uses for your magic and then using Vis to utilize them. Vis comes from 'Aura Nodes' that are scattered throughout the world. Every node has a different maximum amount of Vis. Some are large, some are small. If their Vis is above or below their max, they try to return to normality, and in doing so, they generate Flux.
Flux can manifest itself in the world in a variety of ways. The most common way is the spontaneous generation of wisps, little balls of light that float around and simply shock you if you get too close.
Those of you that appreciate automation will be happy to hear that Thaumcraft has a full selection of utilities for automation, such as Hungry chests that eat items that touch it and golems with intelligence to perform a wide variety of tasks like harvesting, sorting items in chests, transporting items, or even helping you perform research.
Hosting should not be an issue.
I'm looking for ACTIVE PLAYERS. If you only want to log in like once a week to place 4 blocks, forget it.