After investigating the other answers, I see a number of options available to directly answer my initial question of a Battlemind's ability to mark at longer ranges.
Student of the Sword
- Allows you to mark on a hit or miss with a one or two handed weapon attack.
Range is dependent on the weapon or power used. Max can be up to 20 squares (javelinJavelin or Fey Strike Weapon for example).Requires
- Student of the Sword multiclass Fighter feat.
- A weapon or power that allows you to make an attack at range with a one or two handed weapon (chosen with feat).
Increases Battlemind's Demand out to 5 squares.Requires
- Demand's Reach feat (paragon tier).
Soldier of Faith
Allows you to use Paladin's Divine Challenge to mark a target within 5 squares.Requires
- Soldier of Faith multiclass Paladin feat.
Hand of Radience/Defending Dabbler - Half-Elf only
- Allows you to use Hand of Radiance to mark up to 3 targets on hit.
Range of 10.Requires
- Hand of Radiance as dilettante power.
- Defending Dabbler feat.
- Ideally you also need a decent wisdom or Adept Dilettante feat, and be able to use implements for it to work well.
Let me know if I have missed anything.