Threads about the monk's usefulness are plentiful in these here message boards :)
After skipping over yet another monk thread I decided to try and make some home brew "improvements" to the most common complaints.
1) Flurry of Blows and High Speed Bonus do not work well together. He deals best damage standing still.
2) The attack bonus of the monk is too low
Focused Training: At first level a monk decides on what aspect of battle he focuses: Speed or multiple attacks.
Speed: A monk focusing on speed does not get flurry of blows. When moving at least 10 ft in a round, he gets a +2 dodge bonus to AC that lasts till the start of the next round.
When doing a charge attack he may forfeit the AC bonus gained from movement and use his Wisdom bonus for the attack roll (instead of Strength or Dexterity).
Lastly whenever he successfully deals damage to an enemy after moving at least half his speed the die size of his unarmed strike or weapon increases by one. Most often this will be a charge attack, but other attacks are possible too like a spring attack, flyby attack or an overrun maneuver with trample (if you get that somehow). Weapon must be a monk weapon of course.
Short Version: Give up FOB, gain +2 AC when moving, Wis for atk on charge and larger damage dice on charge attacks.
Multiple attacks: The bonuses to speed gained from the monk class are halved.
When the monk lands a hit while using flurry of blows he gains a +1 insight bonus to his attacks that lasts till the start of his next round (only for unarmed strikes and monk weapons). This bonus increases by 1 each time the AC bonus from his monk class increases, however it can never be higher than his Wisdom modifier (minimum 1).
Short: Give up speed (bonus halved) and gain insight bonus on attacks in flurry.
Monks can’t overcome DR (when specializing on unarmed strikes)
The simplest solution I can see is to put “Penetrating Strike” and "Greater Penetrating Strike" on the list of monk bonus feats (thus you don’t need to meet the prerequisites) or let monk levels count as fighter levels for this feat.
Diamond Soul is actually bad because your friends can't buff or heal you.
The monk can establish a spiritual connection to a number of creatures equal to his Wisdom modifier. This rather informal ritual takes about 1 minute and last for 1 hour per monk level. Creatures with whom the monk has connected do not need to overcome his spell resistance when casting spells.
The connection to a single individual can be broken with 1 round of concentration. The connection to all individuals can be broken as immediate action (just in case you got in the way of a fireball of your friendly caster and want some additional protection).
Wholeness of Body delivers too little for too much cost
Add the following uses to the ability:
For 1 ki point you can stop a bleeding wound as swift action (you do not heal anything).
If you have ki points left when you fall into the negatives (and are unconscious) you may either spend 1 ki point stabilize or you can spend 2 ki points to heal for the usual amount (possibly waking up again).