You mean mods that will help yourself? Because no modifications really help the server..

 

Moved to help and support section.

 

There are really no mods helpful to the server itself. Some helpful mods that are legal, could be macro, optifine, cjb, or Reis minimap. Some illegal ones are ones that give unfair advantages, or advantages at all, such as nodus, radarbro, or anything that allows you to do something completely afk

 

There's a few mods that can help you on the server. I left some below for you to take a look at. They're all legal, and can help you make some extra money on the server.

CJB - Although mainly used for the fly speed ability, there's other helpful tools within this mod.
Optifine - Great mod. Used almost by every Minecrafter, great if you want to enhance or lower your graphics. Also, Optifine is said to raise your Frames per second you get in Minecraft.
Macro Mod - These can be very helpful when promoting your advertisements, as long as your Macros are under control, you should be fine.

There's many more helpful mods on the server, but these are the main ones I use.

 

I believe that CJB xray does not work on EcoCityCraft. Also, you don't need to download that part.

 

Although X-ray is blocked, (I believe in CJB) if you still find a way around it or use a different mod pack with X-ray, and hit the hot key by accident, there won't be a problem. However, if you're doing this constantly, that's when it becomes a problem.