One thing that the Warhammer designers did really well was to come up with a unique spin on goblins. The iconic fantasy creatures in 'standard' D&D are really rather staid and boring, probably from overuse - and goblins are no exception. In most campaigns they're just low-level mook creatures for the PCs to kill, with barely a second thought. "Oh, look, it's a goblin. Hand over the 15 XP..."
Warhammer goblins have something about them, though. They have style, for one thing. From the night goblins, with their black capes, pointed hats and moon motifs, to the Tupi-Indian pastiche forest goblins, there is a unified look to the Warhammer breeds. I especially like the night goblins: cartoonish it might be, but their demented rumpelstiltskin shtick is far more effective than D&D's rather drab little mini-orcs.
More importantly, though, Warhammer goblins have personality. The night goblins are maniacal drug-addled loons who dose themselves up on fungus before a fight and go running towards the enemy lines swinging ball-and-chains as big as themselves; they herd giant fungus-creatures called Squigs which they sometimes ride to battle; their favourite weapons are weighted nets and tridents which they use to capture their foes. The forest goblins inject themselves with hallucinagenic poisons and ride around on giant tarantulas. Others strap themselves into giant ballistas and hurl themselves at their enemies, kamikaze-like: they are happy to die if only they can have an entertaining death. Warhammer goblins are crazed, absurd, and very, very weird.
My favourite goblin war-method is undoubtedly the Squig Hopper. Imagine a kid on a space hopper. Now imagine that instead of a kid it's a vile, green-skinned, yellow-eyed murderous goblin. Then imagine that instead of a space hopper, it's an orange ball of flesh with a mouth which takes up half its body, giant horns, and two massive feet. Then imagine it bounding across the battlefield towards you with huge, ten-yard leaps while the goblin clings on, waving a cleaver over his head. That's a Squig Hopper. In Warhammer Fantasy Battle the things move entirely randomly, leaving destruction wherever they land (often in the ranks of their own side), and dying in droves. But the concept is just so phantasmagorically cool.
I wish people would give goblins in their D&D campaigns unique flavours like that. But so often they end up being, well, bland.