There's nothing stopping a developer from hosting a web page for his app, which would be page-ranked. And there's nothing stopping me from making an app choice based on evidence other than the in-store reviews. Apps are linked to and discussed and reviewed in all sorts of places all over the web. It works like a charm.

I would love to see side-loading become available for the iPhone, but, knowing Apple, I don't expect it and I don't think Apple should be obliged to provide it.