I agree that it looks like a fishing spider (genus Dolomedes). A close-up of the eyes would make it easier to rule out similar-looking spiders from other families.
Like most spiders, fishing spiders are venomous but not dangerous to humans.
It can be tough, Lycosidae & Dolomedes are very similar in size and appearance, and are very close to each other in terms of evolution.
This one is actually a wolf spider, Lycosidae
The over-all appearance points to this (lack of strong leg annulation/banding, abdominal patterns, etc.) however if you look close enough you can see the spiders posterior median eye glimmering, which is positioned to far back on the prosoma (cephalothorax) to be a Dolomedes spp. and locks this in as a wolf spider.
Both wolf spiders & fishing spiders are not known to be medically significant to vertebrates (you and your animals). Though please know that everyone reacts differently to different toxins, and although allergic reactions are very uncommon with spiders, they are very capable of giving you a painful bite.
The genus may be much tougher depending on your location, and species ID is usually not an option for wolf spiders with an image.
Where was the picture taken?
Last edited by Phil; 05-04-2012 at 09:49 PM.
I agree with Phil on this one. This is some kind of wolf spider, family Lycosidae. Fishing spiders are usually found in the vertical plane (on walls, tree trunks, etc).