All features on a per-biome basis. Many may not work with other mod features due to lack of event calls.

• Disable map gens (Cave, mineshaft, nether_bridge, etc.) (No biome info given)
• Set max spawn pack size for entities (per entity or global) (#65)
• Disable bonemeal use
• Change sky color (#58)
• Port remove late block assignments config option to 1.8 and 1.8.8 (#70)
• Actual filler block metadata (#75)
• Ocean top and filler block metadata

Other ideas:

• Disable sapling growth
• Break speed multiplier (per block or global) (No interest/too weird)
• Break speed override (per block or global) (No interest/too weird)
• Healing multiplier (per entity or global) (No interest/too weird)
• Healing override (per entity or global) (No interest/too weird)
• Disable ender teleports (to and from) (No interest/too weird)
• Disable bed use (No interest/too weird)
• Disable hoe use (No interest/too weird)

List subject to change. Please suggest more features or tell me why an existing one shouldn't be implemented.

Feature request add a random Biome command witch every block by block biome would be random based on an array the user would create in his' or her script.

Feature request to be able to limit the tweak only to a particuar dimension

Maybe I'm not seeing it, but for Mob spawns a "Max per chunk" would be awesome. (1.7.10 please and thank you)

The ability to have grass and foliage color variation on a per biome bases.
Options I would like to see with this feature:
* set the chance for the effect to occur in a biome(Can occur multiple times in one biome)
* set the rough size of the area that would be effected(In blocks)
* set which biomes are effected
* set color of effect

Example of how a script could look. I am still vary much learning how BT works and the different functions it has. There maybe a much better way to do it then 'set', but I hope this gives you a better idea of how it would work

#Specify id
myBiome = forBiomes(1)

#Set the color of the alternate grass
myBiome.set("grassColorVariant"  12308294)

#Set the size of the area that the alternate grass color would effect
myBiome.set("grassColorVarientSize" 15)

#Set the chance of that alternate grass color to be used
myBiome.set("grassColorVariantChance" 5)

And here is a swamp biome for reference sake.