Has anyone disenchanted these? How powerful can the enchantment be? Could you make a pretty decent monk by doing this?

According to http://www.uesp.net/wiki/Skyrim:Combat#Additions_to_the_base_unarmed_damage the maximum fortification enchantment (barring loops ) is 14, though supposedly it can be applied to gloves and rings

Well, if you like giving one hit KO's I suggest using the Fortify Restoration Glitch. Just to up the damage to NON overpoweredness.

so maxxing out gloves and rings, along w/ the Heavy Armor perk... How valid would it be to make a monk? I mean, would it be more work than its worth?

early game sometimes unarmed does more damage than most wpns, end game even with the right enchants and perks (the gloves and vampire blood ring) u will see a damage drop, however if u been lvling alteration-heavy armor skill, u still can tank. I'd say Khajit or Argonian with Heavy Armor + Alteration + Enchanting for skills while doing quests such as Ratway for gloves, Mara's Blessing for magic resist, Pro-vampire quests for blood ring (hp and melee damage bonus), and that Dwemmer quest in rift too. Basically do quests around the rift ^>^.