This Mod Pack contains 35 mods! All mods should work, some of them work only on 1.05 (Pro Pain so far, all other worked for me on 1.07).
Enjoy the mods ^^.
Download all 10 parts.
Unpack it to the main dir of Serious Sam, example: c:\Program Files\Croteam\Serious Sam The Second Encounter
After unpacking it will take 3,71 GB. Be sure to make a backup of your controls and players folders from main Serious Sam, some mods may change the settings.