Sun Soul Monk
Originally listed simply for it's +1 cold damage property in Class Boosters, a second read through reveals;
Prerequisite
member of the Sun Soul monk order (see page 25 of the FORGOTTEN REALMS Campaign Setting and page 41 of City of Splendors: Waterdeep), Monk 6th,
Benefit
This feat's benefit depends on the patron deity of the monastery where you studied.
Lathander: You can channel your ki to turn an undead creature. Once per day you can choose to imbue a single unarmed strike with ki; this decision must be made before the attack roll is made. If you hit an undead creature with this attack, it is turned unless it succeeds on a Will save (DC 10 + 1/2 your HD + your Wis modifier). If the undead creature has turn resistance, it can add this as a bonus on its save. If you have the Stunning Fist feat, you can also expend a daily use of your stunning fist to use this feat. If you have the turn undead class feature, you can expend a turn undead attempt to use this feat.
Selane: Your unarmed strikes deal an extra 1 point of cold damage and count as silvered weapons for the purpose of overcoming damage reduction. When in moonlight or starlight, treat your monk level as three levels higher for the purpose of determining your unarmored speed bonus.
Sune: Your combat style is fascinating to watch. Once per day as a standard action, you can perform a maneuver that fascinates a single creature within 30 feet that can see you (Will negates; save DC 10 + 1/2 your HD + Cha modifier). Creatures of a type different from your gain a +4 bonus on the save. This supernatural effect lasts for 1 round. If you have the Stunning Fist feat, you can also expend a daily use of your stunning fist to use this feat.
Recall that Destroying Undead, Rebuking, and Commanding Undead are internal rules of Turn Undead. So with this Feat a Monk can Rebuke/Command Deathless creatures.
But wait! While the 3.0 FR book notes the Sun Soul Monks has being Good/Neutral aligned in a sidebar, the 3.5 City of Splendors book sets forth actual requirements. The requirement? 20 hours of charitable work and 2 Ranks in either Jump or Tumble. Which means a cleaver Evil aligned PC could join the group to Rebuke/Command Undead. He should probably do this in disguise, just saying.
I think extrapolating the turning effect beyond what is specifically stated is incorrect. "Turned" is a defined condition according to PHB pg 314. "Turned: Affected by a turn undead attempt. Turned undead flee for 10 rounds (1 minute) by the best and fastest means available to them. If they cannot flee, they cower." The Sun Soul Monk feat only applies the Turned condition, not Rebuked, Commanded, or Destroyed.
Deathless would still be Turned, because Sun Soul Monks are not clerics, so the part in the Deathless description that says "Evil clerics can turn or destroy deathless creatures as good
clerics turn or destroy undead" does not apply to them.