Pascal VOC 2012 is common benchmark for object detection. It contains common objects that one might find in images on the web.
Note: the test set is witheld, as is common with benchmark datasets.
You can think of it sort of like a baby COCO.
2 months ago
aeroplane, bicycle, bird, boat, bottle, bus, car, cat, chair, cow, diningtable, dog, horse, motorbike, person, pottedplant, sheep, sofa, train, tvmonitor