The only supplement or fortified food vegans need to pay extra attention to that can't be found in the diet is B12.  Other supplements vegans take tend to be similar to ones that omnivores take such as calcium, vitamin D (vegans take D2 ergocalciferol instead of D3 cholecalciferol because D3 is derived from sheeps wool or fish; or vegans may take a D3 labeled as vegan and derived from mushrooms exposed to UV rays), multi, etc.  Some vegans take a plant based DHA/EPA supplement (derived from sea weed where fish get their DHA instead of the common fish oil or omnivore DHA supplement) for omega 3's.   DHA can not be obtained directly from a vegan diet however, ALA can which includes foods like walnuts, flax seeds, sunflower seeds etc.  There are studies that ALA can convert to DHA in vegans though efficiency of this conversion process varies among individuals.  The vegan DHA supplement isn't a requirement for health but some take it as an extra precaution.  

I take calcium and D and B12 and that is all.  The rest of my diet consists of lots of whole plant foods.  I was diagnosed as an omnivore years ago with osteoporosis (lost both ovaries and other factors) so the calcium/D supplements are a requirement for me personally.  I would recommend vtaimin D to people who live in climates where it is hard to obtain from the sun but calcium can also be gotten in a vegan diet from plant milks, plant based yogurts, low oxylate leafy greens like bok choy, kale, collards, mustard greens, broccoli etc.  Sesame seeds, almonds, and white beans are also good sources of calcium and other bone building minerals as well as blackstrap molasses which is also rich in iron.  I put it on my hot cereal and use it for cooking.

DEVA is a  decent vegan brand that offers a variety of vitamins, minerals, and supplements for vegans.  You can find it online through the vegan store or at Amazon.  There are tons of  hidden animal ingredients in most over the counter vitamins and supplements and most are not suitable for vegans so it is one area to really be vigilent about.  A lot of popular supplements have gelatin in them, or dyes that are animal based.  Not to mention other horrible chemicals.  It is best to get as much nutrition as you can from plant food.  I would recommend the book "Becoming Vegan: The Complete Guide to Adopting a Plant Based Diet" by Brenda Davis and Vesanto Melina, both registered dieticians and nutrition researchers.  They offer an honest unbiased approach and use legitimate scientific studies to back up what they advise and do not follow fad diets.  The book is very comprehensive on how to meet all aspects of nutritional needs on a vegan diet.  You might find it at your local library or you can buy it used for very cheap at Amazon.  

Hope this helps!