I've seen a very effective 28 point buy monk (one of the most effective characters in my region of Living Greyhawk--though there are a lot of other monks who are less effective).
I think he started out as a barbarian:
Half-orc Bbn 1:
Str 17, Dex 14, Con 14, Int 8, Wis 14, Cha 6
After first level, he became an ex-barbarian and started advancing as a monk but he kept the extra hit points, extra speed, and the extra weapon proficiencies (which were very useful until mid levels). At fourth level, I'm guessing he increased his strength and put the rest of his stat bumps into wisdom.
He makes very good use of Stunning Fist, Expert Tactician (hit the foe again after stunning them), Roundabout Kick (hit the foe again after critting them), Improved Critical, etc.
Another highly effective half-orc monk I've seen:
Str 18, Dex 10, Con 14, Int 12, Wis 12, Cha 6
I'm not certain on the abilities and a power gamer would probably reduce his int to bump wisdom and/or dex. However he's pretty darn effective like that.
He makes good use of Improved Grapple and all sorts of grapple enhancing items and abilities (enlarge person, suregrip, etc) and tries to take the most dangerous foe out of the fight by pinning them. He functions best with a cleric standing right behind him and healing the copious amounts of damage he takes but that doesn't keep the character from working. Barbarians work that way too.