Seahorse Hostel: very modern and well decorated building with a coffee shop built into the bottom, and a bar on the top, which gives great views of the city.
Danang Backpacker Hostel: it was a standard hostel, with a bar on the roof with pool tables etc, but the aircon wasn't good enough and it was difficult to get much sleep. Seahorse was the better one.
Lady Buddha: an enormous marble statue visible from all the way along the coast, which faces out into the bay. Very impressive up close and surrounded by smaller temples. Worth a visit if you can get there.
Da Nang Museum: local history museum, tells the story of local ethnic groups and how the city fared in the war.
Marble Mountains: Da Nang is flat, except for these mountains that pop up occasionally. The one we visted gives an amazing view of the coastline, and has monasteries built into the natural caves of the mountain. There are small temples lit only through natural skylights in the roof, and it's well worth a visit. You can either get an elevator up, or walk the stairs. The stairs are quite long and the heat doesn't help, but they aren't hard.
Dragon Bridge: one of the bridges across the river is modelled to seem like a dragon, and will occasionally spit fire. I only saw it from far away but it was pretty cool.
Along the same river there are quite a few bars and clubs with cheap drinks, often with other backpackers in.