i remember hearing at some point that monks were more powerful than the other classes (3.0 maybe?), i dunno
i guess that has changed? or i was misinformed in the first place dunno
In both 3.0 and 3.5 the monk is an extremely weak class. Now, like virtually everything in 3.X, with enough splat books you *can* enhance an aspect of the monk enough to be significant or overpowered, but it is very, very hard.
The biggest problem with fixing the balance issues inherent in the non-spellcasters is that their damage output is generally adequate to powerful (monks do have more problems here than, say, a barbarian), as long as everything goes to plan. However, they have nothing else, and things generally don't go to plan (full attacks can be hard or counterproductive to get). The monk could afford to see a BaB boost, but beyond that you need utility effects and, as mentioned, the ability to do lots of damage W/O taking a full attack.
If you have access to it, the book of 9 swords provides the Swordsage and the Warblade, both of which might work for you, especially if you focus on the less "magicky" powers.