It was nary a week ago that I came to you with news that a modder named ColdTyrant had ginned up a system to keep keep going forever: bolting on a whole Hitman Freelancer-esque contracts mode with an accompanying gacha rewards system. It was cool as heck, and is now old news—ColdTyrant has returned with , which does the same thing 
for the Gray Fox's gang.
Just like the DB quests, this is essentially a 
quest-generation system in the vein of the radiant missions you get in Skyrim. "Take on Radiant Special Requests to steal specific items throughout Cyrodiil," says ColdTyrant, boasting of "100 infinitely repeatable, randomly selected quests to obtain specific items for anonymous clients."
It works, well, a lot like the Dark Brotherhood mod. You pick up envelopes with contracts on them from a new table in Dareloth's Garden and head off to filch whatever it is that needs filching. Once you've deposited your lucre in a drop box, you'll get a leveled gold reward (all the way up to [[link]] level 30) plus some points of a new currency called Fox's Favor.
Unlike the Brotherhood mod, which saw [[link]] you spend its currency on its gacha scamp (yep), you can exchange Fox's Favor for Thieve's Guild services: wiping your bounty, your infamy, getting lockpicks, or getting special gear.
I love the idea behind both of these mods. Replaying Oblivion, I think a big but under-discussed reason everyone remembers the Thieves' Guild and Dark Brotherhood so fondly is that so many of their quests take place in the game's bustling clockwork cities, where the legitimate guilds are constantly sending you out to caves and ruins that don't have anything in them but monsters. It's way more fun to sneak into a shop while the owner's asleep upstairs than it is to plumb the depths of yet another ruined fort, and mods like this let you do it forever.
Still, if you do want the legal guild quests [[link]] to go on forever, ColdTyrant has you covered: and do much the same thing for those two factions, letting you constantly do new quests instead of checking out once you become guildmaster. Not bad for a game with no official mod support.