I've been thinking of some new challenges, let me just rattle them off two of them:
First, I've been thinking about that "Angel of Avarice" challenge mentioned earlier, and I was inspired with something similar.
Angel of Capitalism
PAH! Sure, the demons are bad and all, but this is all business, and hey, if you kill the Cyberdemon, that's just good PR. In this challenge, No globes, medkits, armors, uniques, or randomly generated items of any kind will be spawned on any level. Also, no monsters give any experience, and any monsters that would normally drop weapons/ammo (former humans, seargents, etc) won't drop anything either. Instead, all monsters drop a certain amount of money, with the amount varying with some randomness but with stronger monsters generally having more money. This money doesn't do anything by itself, but inbetween each dungeon level, you enter a shop. This shop is reminiscent of the trait selection screen, and in here you can spend the money you’ve collected.
Your choice of purchases include:
All manner of globes, including invincibility globes and Megaspheres, which take effect when you enter the next level.
All manner of items, including Nukes.
All manner of normal armor,
All manner of “normal” weapons, including the chainsaw and BFG
All types of ammo
You can purchase a random Unique
You can purchase a level up (this one gets progressively more expensive, of course)
After you’re done with the purchases, you just exit the shop and into the next level. All items will be priced accordingly, so of course while BFG’s, invincibility orbs, uniques, and nukes may be available, they would be so prohibitively expensive that you couldn’t buy them without first saving up and denying yourself other important things.
To keep up with the theme of the challenge, I think the special levels should have their rewards altered where, instead of being items, they’re big piles of cash equal to the items you’d normally receive.
One last thing, I think that the Angelic Armor and the Longinus Spear are iffy items, since they’re these weird cross-breeds between uniques and normals, so I think that while these items can be bought, they have to first be unlocked by completing the corresponding special level.
Angel of Gauntlet
Each level starts with no monsters on it. However, in this challenge, there’s a new type of structure, the spawner. These spawners are stationary and have HP much like creatures do. These will spawn a certain creature infinitely until it is destroyed. Now, of course, the stronger monsters will have much longer spawn rates with the weaker monsters having much shorter spawn rates. These spawners are structures, and thus don’t leave corpses that can be revived by either Archviles or Nightmare! difficulty.