Most of the Necromancer minions have a secondary use anyway - Blood Fiend to be sacrificed to heal a portion of health a la Healing Signet on Warriors, except worse. Consume Conditions is a far and away better heal (more initial heal, + more heal for every condition removed)
Bone minions to be living bombs, though you had to wait for them to engage an enemy before detonating them (unlike Mesmer clones which run up to the enemy THEN detonate). They're super fragile.
Bone Fiends aren't terrible. They have ranged attack, deal more damage than the Blood Fiend and Bone Minions (who aren't being exploded), and can immobilise foes at a cost of immobilising themselves - but given their attack is ranged, being immobile doesn't matter much. But if you want to control foes, why not use fear skills? Not only does it remove movement control from them, but it also prevents them attacking, unlike Immobilise.
Flesh Wurms are a useful method of teleporting. It's one of Necro's few mobility skills, a la Blink on the Mesmer. Summon flesh wurm, it remains where it stands, attacking - use its move again, and you teleport inside it and telefrag it. Some builds use it, though I'd really recommend just having the Well skills there instead for their superior damage. And Necros aren't meant to be mobile - that's what you have your life force for.
Flesh Golems are probably the best, if only because they're tankier, and have a launch-and-knockdown move at your command, as well as doing respectable damage.