Dr Atkins recommends quite a variety of supplements and I have bought his basic 3 and Omegas when they were on 2 for 1 at Boots, from what the packet says they are much the same as a 'good' Multi vitamin and oil supplement.

I currently use Centrium multi vitamin and an Omega oil capsule just to be sure as when I did induction only taking a cheap multi vitamin I did get a feeling of muscle weakness (like I'd excercised hard the day before) especially walking upstairs, it disappeared as soon as I started on the basic 3.
Of course it could all be in my mind but I'm happier taking something for insurance.

I don't know what other regimes recommend but the Atkins book has a whole chapter on vitamins (as I remember, my copy is out on loan) but you'll find plenty of information on the forum.