One of my favorite things to do with 4e, especially with the character builder, is create characters with a theme. Sometimes that theme is just to make that character as powerful as possible, while other times its to use a certain subject, be it crunch or fluff, and run with it.
A major aspect of this can start with which race you pick for your character, and the racial power is a big part of that.
Dragonborn - Who doesn't want fire breath?
Half-Elf - Get another class's at-will as an encounter power.
Human - Get an extra at-will.
Bladeling - Explosion of spikes attack!
Fire Soul Genasi - Immediate reaction fire attack.
Minotaur - Charge and use racial attack.
Orc - Attack and use a healing surge.
Tiefling - Bonus to attack and damage if enemy hit you.
Deva - Bonus to attack, saving throw, skill or ability check.
Goliath - Resist 5 all for a round (scale up with tier).
Half-Orc - Extra damage on hit.
Longtooth Shifter - Damage bonus, regeneration.
Razorclaw Shifter - speed bonus, and bonus to defenses.
Bugbear - Bonus damage when you have combat advantage.
Storm Soul Genasi - Extra damage with thunder attacks.
Githzerai - Bonus to all defenses.
Gnoll - Extra damage on a charge.
Elf - Reroll a missed attack.
Halfling - Enemy rerolls a hit.
Eladrin - Teleport 5 squares.
Water soul Genasi - Shift up to your speed.
Wind Soul Genasi - FLY!
Githyanki - You or youally fly.
Goblin - Shift when missed by an attack.
Kobold - Shift as a minor action.
Shadar-Kai - Teleport and become insubstantial.
Dwarf - No racial power, but more features than you can shake a stick at.
Gnome - Turn invisible and wizard's cantrip.
Doppelganger - Can shapeshift into another humanoid.
Drow - Create a cloud of darkness or outline an enemy to make them easier to hit.
Earth soul Genasi - Knock enemies prone.
Hobgoblin - Automatically get a saving throw when you get a condition that a save can end.
Warforged - Gain HP or temporary HP.
I donno about you, but writing this has given me some more ideas for characters. It would be difficult but a fire soul Genasi that focuses on immediate interrupts, or a half-elf/dragonborn/bladeling that has as many encounter powers as possible. Ok, both of these are tricky build ideas, but can you think of any better ones based on a racial power?