As an example (I am assuming that the standard races are the "only" races): No standrad race (unless you called aasimar, or drow a standard race) gets an increase to CHA. Let say a 15 level human bard had 18 CHA. You could increase that CHA ONLY by:
(1) increasing your CHA with your ability choice increase you get every 4HD,
(2)getting items that increase CHA,
(3)getting racial MODS to CHA,
(4)getting PrC MODS (which most PrC MODs WOULD NOT give you an EFFECTIVE increase to all CHA but you would simply give you a +2 to CHA or whatever, so really PrCs arent what your looking for),
(5)getting magic MODs,
But again NON of these MODS are stackable (yes amny magic MODS are stackable but take those INTO consideration), and the ones that are stackable (like ones that you get through PrC's arent that varied). (obviously increase in CAH means increase CHA based checks but again you are not looking for increase in CHA your looking for increase in EFFECTIVE CHA that is not based on items, etc)..
So your friend is UNTYPED bonuses...