One of my issues with the multiclass feats is that I spend feats to pick up these neat new abilities, but since they don't use my primary stats in many cases they are inherently weaker than your normal powers. So here are some examples to help with that.
Martial Wizardry
Prereq: Str 13+ or Dex 13+
You channel arcane power through your weapon, and with a powerful swing release it upon your enemies.
Benefit: When using an arcane power with a range of close or melee, you can use your str, con, dex or cha modifier for the attack and damage.
Special: You can use a martial weapon as an implement when using these powers. This only grants you the magic weapon bonuses to your attack and damage, you do not get proficiency bonuses and the base damage of the power does not change.
Tactical Sniper
Prereq: Int 13+
Though not the strong or fastest fighter, you can pick exactly the right time in combat to release a deadly strike.
Benefit: When using powers that have a range of area or ranged, you can use your intelligence modifier for the purpose of attack and damage.
Martial Wizardry
Prereq: Str 13+ or Dex 13+
You channel arcane power through your weapon, and with a powerful swing release it upon your enemies.
Benefit: When using an arcane power with a range of close or melee, you can use your str, con, dex or cha modifier for the attack and damage.
Special: You can use a martial weapon as an implement when using these powers. This only grants you the magic weapon bonuses to your attack and damage, you do not get proficiency bonuses and the base damage of the power does not change.
Tactical Sniper
Prereq: Int 13+
Though not the strong or fastest fighter, you can pick exactly the right time in combat to release a deadly strike.
Benefit: When using powers that have a range of area or ranged, you can use your intelligence modifier for the purpose of attack and damage.