At least my diet is very high in vitamin A with all the sweet potatoes, grass fed butter, free range eggs and especially organ meats I eat. This would seem typical for most paleo advocates as well. With that said, I don't think a vitamin A supplement is necessary. Fish oil can go rancid quickly too and includes some extra PUFAs (even if they are O3's) that you probably don't need. So if you aren't devoid in the foods I listed I'd avoid that supplement. I've been reading in several places recently that probiotics are expensive and unnecessary in that they'll add temporary flora but not build up the ones in your gut, but won't hurt you either.
The D is definitely good if you don't get enough sun.
One thing some paleo peeps don't get enough of is iodine, since it isn't unusual for someone to eliminate most salt when they go paleo. If this is the case for you kelp tablets could be a good supplement, they also have trace amounts of other important minerals.
Acerola berry is also a great supplement for vitamin C and antioxidants. If you try to lower your fructose content due to all the villainy being placed on this energy source then this is especially a good idea. You can never get enough C though and it tastes good.
If you aren't yet eating organ meats, grass fed butter and free range eggs, get some K2 in your diet. Dr. Price's orders ;).
Finally, I second the magnesium suggestion. Our soils are simply so depleted that this is hard to get through your diet in adequate amounts.