My thoughts (based on my experiences) with Monks:
Half-elves make great monks, the best race if you plan on dual classing to a non-racial secondary class without maintaining an equal balance between classes. Also, they get many elven affinity bonuses, though reduced in power. For this, they give up the "non-human" bonus feat. (Whoopee, you'll never notice it.)
Dwarves are good monks. Very excellent constitution. They have to be supported heavier in the "persuade" skill. It's not a terrible burden, but it does suck up a few extra skill points. Plus dwarves have all those great affinity bonuses and training. Run a dwarf monk into a nest of orcs, goblinoids or giants and see just how well he/she performs. [img]smile.gif[/img] If you're planning on multi-classing, dwarves add nothing special (fighter, whoopee!).
Humans make good monks, but not the best. They're best attribute is the extra skill points, what-not, they get, plus the easier multi-classing.
Elves are good as monks, but blow on constitution so you have to take the toughness feat. But they are pretty good against magic using creatures and they have a lot of affinity bonuses. If you want to be a monk/wizard, this is the race for you.
Half-orcs make good melee-oriented monks, but their portraits all suck. More importantly, since they're stupid AND ugly, it's harder to get all the skills you need because you have to put so many of your so few points into Persuade.
Halflings are poor monks, unless you want your monk to sit in the back and throw shirkun instead of kung fu fighting. If that's the case though, make him a barbarian or a fighter or a ranger and take exotic weapons.
Gnomes are terrible, terrible monks because of their strength/size penalties. The worst class for monkdom. Only use if monk will be the secondary class to wizard.