Hey Tim, I love what your doing, this was a passion project and something of great interest to me in the past, but unfortunately I let it fall to the wayside. I in fact started a list in the past on my blog then migrated it to a back page on our store website, just for temporary hosting. Here it is. I know @pennsif was also keeping a list at one point as well and may be able to help you with some other services.
We do also accept steem/sbd at checkout at www.phelimint.com, I know it's been mentioned and I'm not actually interested in the bounty.
I would be happy to help you on your quest in anyway, it's still something of great interest and passion to me.
I know we were able to integrate a simple script I found on our shopify store to accept the payments and I'm sure someone with real programming chops could modify it for other e-commerce platforms, I do think there are lots of other entrepreneurs here on the steemit platform that could benefit from that and I think it would really help our currency grow. Here's that post with the scripts
Please once again let me know if there is any way I can help you with this project.
Awesome, thanks!
I just launched my site to list all the businesses accepting STEEM/SBD :)
You can read about it here.