This Golden Orb Weaver spider set up residence on our back deck a couple of weeks ago. The other day it caught a large beetle and ate it in only a few hours - now it's much fatter than pictured here. Don't worry, these spiders are common and harmless.
Update: After she got fat on the beetle, a small male turned up and spent the next week in the web with her (the male is tiny compared to the female). Last night (Sun 6th Nov) she started climbing around our balcony - we were very curious what she was doing and thought she was looking to move to a new location. But this morning we found still in her web - much skinnier, even skinnier than pictured here! She had laid a marvellous big golden webb'd eggsack up underneath the gutter. Baby spiders on the way! Lets hope she catches another big beetle to make her fat again.