I am running a necromancer at the moment.
There are a few things I would recommend, but please do bear in mind that my build specifically stays away from undead minions (it's a RP thing)...
Half-Elf Bard 1 / Focussed Necromancer 1 / Cleric 3 (Death & Dream Domains) / Mystic Theurge 5 / Sublime Chord 1 / Fochlucan Lyrist 9.
To answer many questions:
Yes, Skill Points are extremely tight.
Yes, it does use the chenanigans of Versatile Spellcaster.
Yes, it is an end-game heavy hitter, and can be quite weak early on.
Why do I like this build?
Access to 9th level Cleric & Wizard spells.
Access to Complete Champion's Charnel Miasma Reserve Feat.
I also utilise the Song of the Dead from the Dragon Compendium, and Fell-Frightening from Libris Mortis.
You see, this build is a Lawful Good undead slayer type. It's not enough to be able to blast undead. You have to be able to make them fear you.
The half-elf bard thing helps with low-level Diplomancy in early game, then using fear in mid-game, then spells in end game.
That's the rough build, I can expand on it should you wish.
Oh, and a Slaymate is very powerful in this build.
And to answer a final unasked question, I do love fear builds.
Hope this helps.
C.