The Trample feat...

... is a bit of an oddity among the mounted feats, isn't it?

• It gives your mount an additional ability, rather than the rider.
• It almost explicitly refers to horses, or at least horse-like creatures (hoof attack)
• And it does not give the trample special ability, though it is a similar concept.
  

Semi-Random Crunch - The Cavalry Line

I mentioned previously that I wanted to talk abou the cavalry line. I feel that the basic idea can already be found in the SRD, in a different context. I a cavalry line, each member would occupy less space than normal. What other rule is there that does the same? Squeezing!

A quote from the SRD:

Squeezing: In some cases, you may have to squeeze into or through an area that isn'’t as wide as the space you take up. You can squeeze through or into a space that is at least half as wide as your normal space. Each move into or through a narrow space counts as if it were 2 squares, and while squeezed in a narrow space you take a -4 penalty on attack rolls and a -–4 penalty to AC.
When a Large creature (which normally takes up four squares) squeezes into a space that'’s one square wide, the creature'’s miniature figure occupies two squares, centered on the line between the two squares. For a bigger creature, center the creature likewise in the area it squeezes into.
A creature can squeeze past an opponent while moving but it can'’t end its movement in an occupied square.
To squeeze through or into a space less than half your space'’s width, you must use the Escape Artist skill. You can'’t attack while using Escape Artist to squeeze through or into a narrow space, you take a -–4 penalty to AC, and you lose any Dexterity bonus to AC.

The -4 penalty to attacks and Armor Class is likely too high, and since the "obstacles" are not as solid and unmoving as a wall, it can easily be reduced.

Forming a Cavalry Line: Mounted characters trained in the Ride skill can form a cavalry line, as long as each member is trained in the skill. In a cavalry line, the spaces of two Large or larger mounts may overlap, as long as no mount completely shares the space of another mount. Each member of the cavalry line takes a -2 penalty on attack rolls and AC.

Example: Riders x, y, and z forming a cavalry line:

xyßz
xyßz

Rider x occupies the x and y squares. Rider y occupies the y and ß squares. Rider z occupies the ß and z squares.

Rider of the Line [General]
You are capable of fighting in a cavalry line more comfortably.
Prerequisites: Ride skill, Mounted Combat
Benefit: You do not suffer a penalty to your attack rolls while in a cavalry line.
Special: Fighters may take Rider of the Line as a fighter bonus feat.

Semi-Random Crunch - Dire Voice

Since I anticipate there will be some large amount of howling on ENWorld when it gets back up, here's a feat that'll help :D

Dire Voice [General]
Your voice carries great power and threat.
Prerequisites: Charisma 15, Persuasive
Benefits: You get a +2 bonus on all Intimidate checks.
Add +1 to the Difficulty Class for all saving throws of your racial sonic special attacks, exceptfor spells.

Balance-wise it is half a Persuasive, and one or more halves of Ability focus. In most cases, the one who takes this feat only will have one such special ability, but a few creatures benefit more from it, for which I added a few prerequisites.