If you want a monk-ish character who can do an incredible amount of damage, have amazing AC, and do it without a lot of equipment, go for the Enlightened Fist from Complete Arcane.
I have an 11th level one that I stopped playing because I felt the build was to powerful. (Mainly due to one spell (Wraithstrike), but the DM didn't seem inclined to ban or errata the spell.) Admittedly, this build would be difficult to play from level 1, but starting at lvl 12 it's a powerhouse.
The build I used: Human Mnk2/Sor4/Enlightened Fist 6
- on 32 point buy, set your Charisma to 16, Wisdom and Int to 10, then buy all your other stats up to 14.
- bump your charisma at lvls 4, 8, and 12
Feats (and the level I took them at)
1) Practiced Spellcaster (sorcerer)
1) Combat Casting (human bonus feat)
1) Improved Unarmed Strike (monk bonus feat)
1) Stunning Fist (monk bonus feat) - 10 uses at 12 lvl with this build
2) Deflect Arrows or Combat Reflexes (monk bonus feat)
3) Empower Spell
6) Ascetic Mage (You now use your charisma instead fo Wisdom for AC bonus, sorcerer levels stack with monk levels for AC bonus, and you can sacrifice a spell to gain a bonus [equal to spell level] to attack and damage with all unarmed strikes for 1 round) - from Complete Adventurer
9) Arcane Strike (you can sacrifice a spell to gain a bonus on attacks equal to it's level, and bonus D4's on damage equal to it's level for one level) - Complete Warrior
12) whatever you want
This is the gear I bought at 10th level with 49,000 gp
Cloak of Charisma +2
Gloves of Dex +2
Amulet of Health +2
Vest of Resistance +2
Hewards Haversack
Monks Belt
Boots of Speed
Potions of Enlarge Self and Lesser Restoration
With 61k, I'd increase the cloak of charisma to a +4, giving you a total Charisma of 23
At this point, you have the following abilities
Normal AC: 28 (+6 Greater Mage Armor, +6 from Charisma, +3 from Dex, +2 from monk/sorcerer/fist levels, +1 from monks belt)
AC Buffs: Shield (+4 AC), Alter Self to Troglodyte (+6 natural armor) or Polymorph to Green Hag (+11 Natural Armor, but lose 2 points of Dex, for a net +10 AC). Max AC = 42, plus any deflect bonuses or other AC buffs you can scrounge up.
Caster level: 12, spells as an 8th level sorcerer
Base Unarmed Damage: 2d6+2 (as a 13th level monk, due to monks belt)
Attack bonus: +9/+4
Flurry: +7/+7/+2
with Haste: +8/+8/+8/+3
Doesn't seem like much, until you add in the spell and class boosts:
Before your attack:
Free Action - activate boots of speed
Free action - activate Fist of Energy (burst) at a cost of one stunning fist use): +1d6 fire/electric damage, plus an additional 1d10 on a crit.
Free action: sacrifice a 4th level spell to your Arcane Fist feat: +4 attack, +4d4 damage per strike
Swift Action: Cast Wraithstrike - now all your unarmed strikes are touch attacks that ignore DR, natural armor, and armor. (If you don't cast Wraithstrike you can instead sacrifice a spell to your Ascetic Mage feat for a bonus to attack and damage, but Wraithstrike is usually more effective.)
Arcane Fist: spend a stunning fist use to cast an Empowered Shocking Grasp during your attack, for another (5d6)x1.5 damage on a single attack.
Final results: touch attacks at +12/+12/+12/+7 that do 2d6+2+1d6+4d4 per hit, and an empowered shocking grasp on one of the hits. Average damage is 22 per hit, and an average of 113 points if all strikes land, plus the shocking grasp.
This goes up even more if you have polymorphed into a Green Hag or Annis Hag (base 3d6 unarmed damage, plus your strength is now 25 instead of 14, plus potential natural weapon attacks and Rend in addition to the flurry).
Big downside: You are burning through 2 or 3 spells a round (fist of energy, arcane strike, wraithstrike) and 1 or 2 stunning fist uses a round (arcane strike, fist of energy). So for 1-3 combats you are a god. After that you are decidely sub-par, although you still have a good AC.)
You can use spells to increase your combat and "cool move" options - Empowered Ray of Enfeeblement, Jump, etc.
It's a complicated build, and has a definite weakness if you expect multiple fights in a row without rest, but until that point you are a very powerful melee combatent for your level.