For the database I'm planning to use Amazon's Dynamodb. It's nice in that it's a NoSql database hosted by and managed by Amazon so I don't have to worry about setup or managing instances or anything like that. It's also pretty fast and relatively cheap. Billing is done on a per request basis.
Because I'm using one Amazon service, it makes sense to use other Amazon services as well (quicker inter-service communication). So to host my app I've been looking at Heroku and Nodejisu. I'm pretty sure Heroku uses Amazon EC2 as a back end and Nodjisu can be configured to use Amazon EC2. Right now I'm leaning towards Nodejitsu because of its connection with Joyent (the company that develops node). Also, it allows websockets. Not that I think I'll need to use them, but who knows.
I'm going to be hosting my code repository at BitBucket because they have free private repos. I know they practically copied GitHub in every respect, but hey, that's capitalism. If GitHub offered free private repos (even if they were to restrict the free option to a single commiter) I would totally switch.
For the checkout portion of the site I'm probably going to go with Amazon integrated checkout. Or maybe I'll have multiple checkout options... But probably not paypal. I've heard stories of them freezing peoples accounts for no good reason. One thing I've learned from years of software development however, is that I do not want to ever write my own checkout again. It is a headache and a half.
I think that about covers it. I'm looking at twitter's bootstrap to get something up quickly that looks nice. Also, I'm going to be using Sublime Text 2 as my editor. Hopefully I can knock this thing out quickly and get back to the game stuff.