Açaí berry has one of the highest ORAC ratings of all fruits, it's the top of most of the lists. Don't know how it tastes or how to eat it though.

Cacao is right under Acai, but you have to eat it with fruit or a sweetener to counteract the bitterness if it's pure. Organic & fermented cacao nibs with fruit is as good as it gets (antioxidant-wise) - besides that there are a few chocolate makers who offer some minimally-processed, high-cacao chocolate bars (Taza's a recent favorite of mine).

Red wine and teas (camellia sinensis, not herbal) are both pretty well-known, although both should be taken in moderation (like chocolate); wine because of alcohol, green tea because of caffeine and teeth staining.

Berries (blueberries, raspberries, cherries, etc.) all have high ORAC values, after that basically any vegetable is going to have a decent amount.

There are a lot of exotic foods & extracts being touted for their antioxidant properties, but you can get a ton of antioxidants from whole (regular) foods that are cheaper and easier to incorporate into your daily diet. I don't see anything wrong with eating a specific fruit for its antioxidants, but I wouldn't go crazy with super-high "superfoods" - antioxidants aren't a holy grail, just a part of the puzzle, and moderation is key.

Here's a list of ORAC ratings:

http://www.mizfrogspad.com/Diet/antioxidants.htm