Also, if you have the Tome of Battle: Book of Nine Swords, you could take the Martial Study feat at some point (3rd-level or later) to gain the Shadow Blade Technique, which is a maneuver that you would be able to use once per battle. It's helpful for improving your chances of scoring a hit.
But more importantly, it would allow you to take the Martial Stance feat afterward, to learn Child of Shadow or Island of Blades, and then after that you could take the Shadow Blade feat. That feat lets you apply Dexterity to damage with certain weapons (including unarmed strikes) while using a Shadow Hand stance (such as Child of Shadow or Island of Blades).
If you took Martial Study at 6th-level or later, you could instead gain Cloak of Deception (turns you invisible until the end of your turn when you use it), then take Martial Stance at 9th-level or later for Assassin's Stance (gives you 2d6 Sneak Attack, like a rogue), then take Shadow Blade at 12th-level or later.
Also, Tome of Battle has a few more useful feats for monks, like Snap Kick and Superior Unarmed Strike.