Anyone who knows about mods should already know about this site. Those of you who were on the fence about them, but are considering trying them, might not.
Twallan, the site owner, is one of the best and most responsible modders in the community. He is knowledgeable about how things work in the game, and his mods are always of the highest quality. He is quick to update his downloads, and has always been more than happy to address technical issues you have with his mods.
His biggest, and most well known mod is Master Controller
. It's primary purpose is town population management, and gives you complete control over the Sims in your town. You can manage them individually, by demographics, or even as an entire group. It allows you to see the status of any Sim, and much more.
The best part about this mod is that it's modular, and has optional mods that are designed to work with it (meaning they won't function without it). These mods do things like add additional functionality to the original mod (extra cheats), expand the possible tattoo locations, change how CAS works, expand relationships in the family tree, and even offers a more active version of Story Progression that actually tells you what's going on in your town
! Non-active Sims will be more apt to find jobs, get promotions, train skills (where the skill objects are available to them), form relationships, end relationships and move to more reasonable accommodations.
Two other mods worth mentioning are Overwatch
and Error Trap
. Overwatch corrects the common bugs and glitches that plague us all, while Error Trap does clean up on your saves (helping to keep them reasonably sized) and provides error reports that can help to troubleshoot game related issues.
He has far too many mods to really mention in his library, but these are three that I don't play without.
You can find the whole list at NRaas Industries