Where can I look for mount-less paladin variants?

[Brace Cormaeril]

Anyone know of WotC material on paladin variants without mounts? What's the trade-in value of a special mount?

 

[Gloombunny]

PHB2 offers a "charging smite" ability in exchange for the mount.

 

[Quez The Lame]

Complete Champion - "Underdark Knight".
Dungeonscape - "Divine Spirit"

 

[Elder-Basilisk]

You can also look into the Pious Templar prestige class.