Suggestion:
Implement Real[tm] Prestigeclasses.
This game bases loosely on DnD 3.5E, and a huge amount of fun came out of all those limitless Combinations of different classes.
All those PrestigeEnhancements are nothing than pale in comparison.
I would like to see a Mystic Theurge (Arcane/Divine Combination), a Tempest (TWF Specialist), a Archmage (THE Wizard), a Blackguard (Evil Fighter), UrPriest (Atheist Divine Caster), Chameleon (Jack of all trades) etc pp. There are so many choices, all the combinations would make hundreds of possible characters.