I first discovered this lot in the dot com years. My coworker who was from Berkeley would always park here when we would hit Triple Rock or Jupiter, and it became a longtime standby for me whenever I couldnt find parking on a busy night in Berk-town. There's often spaces in it even when its really busy. The downside, which is why this is +3 only, is that its metered, but you can work with that. We always managed to.
Location: Entrance is on Hearst between Shattuck and Oxford, on the south side of Hearst. So if your rolling down Oxford, towards the north, you turn left on Hearst and then make another left into the lot. It's super sick parking and it's one of Berkeley's best-kept secrets!