Dolphinesque, if they are as tiny as blueberries, like you said, you probably were given champagne grapes. As darkstream said, these are best eaten plain. They'd make a great accompianment to a cheese plate or fruit salad. Here's some info I found about champagne grapes:
"The first raisins were most likely sun-dried - 3,000 years ago, or so - grapes were harvested and laid in the sun to dry - a process that continues today. The Champagne Grape, Zante Grape or black Corinth Grape are enjoyed fresh as more growers offer this fabulous grape. The source of the dried currant is the champagne grape - a nutritious - great source of B vitamins, iron and potassium - high fiber food that was a precious trade item in the ancient Near East and Rome. Currants and raisins were brought to Mexico and California in the 18th century, and today the San Joaquin valley of California produces almost all of the commercially grown raisins, and represents about half of the total world supply! The raisin industry in California boomed in the late 1800's after a severe heat wave dried the grapes on the vine.
Currants from the Corinth Grapes are seedless and very dark in color - about ¼ the size of other raisins. They are labeled "Zante Currants", which refers to the Greek island where the Corinth first grew. The name Zante is the name of a tiny island off of Greece, and the black Corinth is named after the ancient city of Corinth.
The petite champagne grape is very elegant, and stands on its own eaten fresh,or added to fresh fruit and vegetable salads. It is high in sugar and has a very unique flavor. Handle this delicate grape with care - drape a small cluster on the side of a wine glass for that special occasion. Put a whole cluster of the champagne grape in your mouth and enjoy its crisp texture and sweet taste. "