Recently I have started playing COD4 again.
I found this UK based server that only has new custom maps in its rotation.
They have 230 levels, instead of 55, but from the first level you can choose every weapon and perk. There are no challenges, you just level up by playing. Downloading takes some time, each map is about 45MB.
CG, sharpen your knife! Ren, get your Uzi out! It's great fun!!
Server name: insane.hardcore new maps
Number of clients: 64
IP: 193.47.83.233:28934