myHealtheVet is a Java application on an Oracle database. It does not talk a lot to VistA, but when it does, it uses VistALink J2EE code. I don't think it's easily deployable outside of the VA, but we do have the source code somewhere in the OSEHRA Technical Journal. Most of its functionality exists outside of VistA; I think the only reason it ever talks to VistA is to send refill requests. But I think it just mostly talks to the CDW to get the patient data.
There is KRM's HealtheMe; but I don't know where that lives anymore; I think it's also on the OSEHRA Technical Journal.
I heard from the grapevine many years ago that Oroville Hospital and their system wrote something on top of VistA using some variation of EWD.
I don't know what either Medsphere or DSS is doing for their clients to be honest.
If I were to build something from scratch, I would use QEWD, but unfortunately you have to build the entire security system for patients, as there is no way to authenticate patients in VistA. Note that unfortunately, like any node.js technology, you basically need to keep your stack current every month as new vulnerabilities keep coming up.
This could be a good collaborative project, if people were interested.
--Sam