My favorite so far is http://www.tesnexus.com/downloads/file.php?id=3066 it may not be as loaded with features as others but its nice. You can recruit any NPC and they can do alot of things depending on what there skills are( whatever there majors are determines what they do)
What they do depends on what you're looking at.
If it's...
-Locked- A party member with security as a major will unlock it.
-A container- A party member will loot it.
-A non-hostile NPC (whilst sneaking)- A party member with Sneak as a major will pickpocket them.
-A hostile NPC- A party member will switch combat target to them.
-A party member (in combat)- A party member under orders to heal in combat,will heal them.
-A party member (out of combat)- Party members with Armourer and Restoration will heal and repair the NPC to tip top condition.
You can also order NPCs to brew potions, harvest plants, form squads, bodyguard other NPCs, meet you at pubs around Cyrodil, ride horses, teach them new spells, or even define meeting places yourself and get them to meet you there.
The mod is built for compatibility and flexibility, and will work alongside any and all companion mods, overhaul mods and so on, as well as allowing custom companions to be created with the minimum of effort.