The green tile on your blog looks similar to the revival olive subway at Mission Tile West. Check out some of their trims and borders, your might be able to pull out the hint of red in a small diamond in the border, etc....Look at the Revival line.

Here is a link that might be useful: Mission Tile West

Posting the link to make it easier.

Here is a link that might be useful: Denversquare's kitchen

You could always skip the bs (that's what I'm doing with my soapstone), but here's a picture of one that I liked because it added some interest - you could add a tile like the black (not necessarily black - but whatever contrasting color you think would look good):

I skipped the BS, and intend someday to do either jerusalem gold 18x18" or Carrara marble subways. So for now, it's just painted, and it has held up pretty well for 2 years.

beadboard looks pretty with soapstone depending on your style. A few people have ming green marble - also pretty. I'm still trying to decide what to put with my soapstone too.
This is from the finished kitchens blog.

Thanks so much for your suggestions, everyone. Yes, cbphoenix, the tiles do have a hint of olive in them when we saw them in person. We were expecting a lighter, more spring green, but I still think it could look nice. I think my husband will go down and check out the soapstone slab in person with the tile and get another feel for it. The tile is such a good price (on craigslist), I don't want to let it go, but I want to make sure it will look nice. I will keep looking around; luckily, this is something that doesn't HAVE to be decided immediately!
Pluckymama, thanks for posting the link. Now I know to do that on my own next time!