An excellent post on how to deal with a potentially venomous interloper. Capture (safely), examine, release.
I myself am a bit of a spider fan. The beastie in this post is a Brown Recluse, aka Fiddleback, a North American spider which I'm told can be found in some australian locations, having made its way over from the states, presumably as a stowaway. Around this area, Sydney NSW, we have our fair share of venomous eight-legged monsters, all of which are fascinating and not likley to harm you if you're sensible.
Most common (judging by the number of times I've spotted them) are white-tailed spiders, Lampona Cylindrata, which made a few appearances at my old house in Pyrmont. Their bite is not unlike that of the fiddleback, causing necrosis of the immediate bite area, a pretty ugly sight but not life threatening.
Next in the line-up, Redbacks, Latrodectus Hasselti, a relative of the american Black Widow and the Katipo of New Zealand. This one's a bit more nasty in terms of bite effects, but you don't run into them much unless you're rummaging in dark corners - they build tangled webs near the ground with an ingenious design. The upper, tangled area is brought under tension by strong elastic threads which are anchored to the ground with sticky blobs. Ground-dwelling insects (like roaches) blundering into these threads are hoisted up off the ground and quickly dispatched.
In fact, There's a web of this style just to the right of my desk, right now, between a bookshelf and a hastily-erected CD rack. Some photos are here - I can't tell if this is a redback without disturbing it, so patience! I'll post a follow-up.
Third in the list of beasties we're likely to encounter round here is Atrax Robustus, The Sydney Funnel Web Spider. Now, I've spent seven years in Sydney, and as a rock climber I do get out into the bush most weekends, but I've still never spotted one of these little monsters. They have the dubious honour of being generally held as the most venomous spider on the planet, and their range is roughly 80km or so around Sydney. They have plenty of relatives around the place, including the Blue Mountains Funnel Web. They're reputedly agressive and have seriously large fangs - one source I've read notes they can bite right through a child's fingernail. Some other trivia about these guys:
1. They sometimes fall into swimming pools, where they can lurk, alive, on the bottom until an unsuspecting pool owner fishes them out. Hilarity ensues.
2. Cats are not really susceptible to their venom, and have been known to bring them in to houses as a gift. "Here you go, owner, a lap full of neurotoxin".
3. Struan Sutherland, pre-eminent poisonous-beastie expert, notes the following: "Funnel-Webs may be found in colonies of over a hundred". Aaaaaaaagh!
There are a number of other venomous arachnids scattered around the country, including some venomous wolf spiders, mouse spiders, and the aptly named 'window spider', aka the Black House Spider, but the three above are the important ones. There are also the large, impressive Huntsman spiders, but they're as harmless as to be cute, and I've often carried one out of the house in bare hands, something I'd be reluctant to do with a redback.
UPDATE: doesn't look like the spider on my bookshelf is a Redback, it's more likely Achaeranea tepidariorum, a relative. It's definitely a theridiid, due to the web construction. Some shots are in the gallery .