Last of ToM:
Acolyte of the Ego +1
Obvious entry is a Truenamer, and the self-buffs possible here make that annoying truespeach DC not as big of an issue. 8 levels will give really nice stat boosts, breath weapon, or a number of other effects. Other classes can get in with Truespeech Training and a few languages, but in general it won't be worth the heavy investment.
Bereft -2
Again, Truenamer entry, but the difference here is that you have to target an enemy DC for the class abilities to work. Combine that with the fact that the stronger abilities all require saves, and its a lose-lose situation.
Brimstone Speaker -2
Cleric w/ Truespeach Training is the obvious entry. You gain a breath attack, and gain the ability to summon outsiders using a truespeach check a limited number of times per day, and lose a level of spellcasting every time you can summon a better outsider. Uhm... how is that better than a straight Cleric??? Just cast Dragon Breath and Planar Ally spells
. There's a core-only PrC just for that sort of thing.
Disciple of the Word +0
A Monk at L6 is the obvious entry, but not the only one (consider a Monk 2 / full BAB 2 or even a Monk 2 / Binder 4). The class fully stacks w/ Monk for unarmed strike, AC, and speed, which is pretty good. Essentially, it adds several abilities (some of which are pretty great) that need a stunning fist usage and a truespeach check. It would get +1, since it adds a lot of nice effects to a straight monk, but in the end you trade investment in truespeach (and Int, usually a dump stat) and non-combat monk abilities for some other effects, and except for 2 in particular (dispel when you hit, DR bypass including Epic DR) the abilities aren't that strong. The problem is that the DCs to activate those class abilities is pretty high, so you need feat and items to invest to make them happen.
Fiendbinder +0
Wizard is the only entry worth mentioning. I have never, ever seen how its worth taking this class instead of Malconvoker or such. That said, it doesn't really lose that much compared to a straight Wizard. Planar Binding spells can gain many of the same benefits of this class, but it costs cash. It also loses 3 spellcasting levels
. Its not worth it, imo, but it does gain an ability to become immune to HP damage for a temporary amount of time, which might be useful in some niche builds.