Warlock Invocations are usually self buffs or indirect attacks.
Plus the class' Eldritch Blast with is a magical attack that scales in damage as you increase in level.
Examples of Warlock Invocations are....
Baleful Utterance: Shatter (as the spell)
Dark One's Own Luck: A save bonus based on your Charisma modifier
See the Unseen: See invisible and Darkvision
Charm: Charm Monster (only one at a time)
Fell Flight: Fly
The Dead Walk: Animate Dead
Wall of Perilous Flame: Wall of Fire
Chilling Tentacles: Like Evards Black Tentacles
Retributive Invisibility: Greater Invisibility (and if dispelled does an area affect attack to all in 20 feet)
Dark Foresight: Foresight
Dark Discorperation: Turn into a magical bat swarm
Those are my favs, but there are quite a few more
Plus there are Invocations that can improve your Eldritch Blast, like enemy debuffs, Fire, Ice or Acid attacks and then ones to improve the range or shape of the attack.
Edit: Oh yeah, plus they get a couple of really neat abilites that let them use almost any magic item, and to make almost any magic item