Thanks Kevin (et al!) - I'm trying to upload another view, but it doesn't seem to want to work... Will keep trying! (BTW, what do the females of this species look like? The ones I'm finding all look the same to me...)

Much the same (perhaps not quite so slim), I think. And they don't have the enlarged pedipalps I mentioned -- these are the male sex organs.

-K

The females are exactly as Kevin described. Here is a nice example of one:
Agelenopsis female:

The chances of actually seeing a female are not as great as the chances of seeing the males...unless you make an effort to try looking in their funnel webs at dusk & dawn, etc. The females stay in the web while the males roam in the dark looking for them. That is why a majority of the grass spiders that you are going to find in your house are probably going to be males who have accidentally roamed there.

Thanks Mandy! OK, harmless to humans - how about my cats & dogs (which find these things great fun to chase around the house!)? I worry because some years back I ended up in the E-vet when a dog was bitten by a spider... Pretty scary reaction!

...can't harm your animals either (I guess there's always a crazy random chance that your pet could have a weird reaction or something). I'm not really sure if I've ever heard of that happening with a bite from the spider that you have here in the photo. But most, if not all, spiders have jaws and fangs and can bite. So even if the venom isn't dangerous to us (or your pets), it might hurt a tad bit in some cases. Most spiders are timid and will run away from you, though. They may be more inclined to bite if they are cornered and poked or squeezed (which pets may do).

...but since you are from here in the great northwest, I'm sure you've heard of the Hobo spider? That particular spider is in the same family as this spider in your photo, and it HAS been know to cause some 'issues'. There is still research being done of course...they are trying to figure out what it is about the Hobo's bite that sometimes ulcerates the skin...like a possible bacteria that the Hobo carries, etc. The Hobo is hard for someone unfamiliar with spider anatomy to ID, but it does have some characteristics in common with the spider in your photo. Here is a great link to a site with all the Hobo info you'll ever need (this site is recommended by Rod Crawford from the Burke Museum because the information is actually true). http://www.hobospider.org/
Another great site: The Spider Myths Site
And another: How to Identify a Hobo

And remember to try to catch the actual spider that bit you or your pets. Should something 'strange' happen you can bring the spider to the doctor with you so they can decide on treatment.

That's a lot of info for ya! It might come in handy someday, you never know. :)

Oh, one more thing: I am curious about your previous incident with the spider bite and the E-vet. Do you know what kind of spider it was? I'm just curious.

I'm clueless about spiders but maybe Mandy or someone can answer. (disclaimer: if you need expert professional advice, check with your local extension office)