The errata'd Ninja of the Crescent Moon works quite well. Enter the prestige class as a 4/3 fighter rogue. That way yoiu'll have weapon specialization, Uncanny dodge, Evasion and 2d6 sneak attack. Later on you get all the "cool ninja goodies". Alternatively you could use a monk level or two.
The class is in Sword and Fist, but you need to download the errata.
