Chezbgone

Blocks that keep Chunks loaded- Lag and frequent crashing

Block Breaker- Grief and Lag

Philosopher's Stone and Minium Stone- Grief

Buildcraft Pipes- Lag (Use Redpower)

Mining Laser- Grief

Tesla Coil- Grief

Mystcraft- Lag

Cannon- Lag (entity)

Here is a list of items that should be banned and why:

Spawners- Entities

TNT and other explosives- Grief

Wireless Redstone- Lag

Nuke- Grief

Nuclear Reactor- Blows Up

Ender Chest- Crashes server

Spawn Eggs- Grief and Lag

Continued list on other post