Out of curiosity, what do you need a database for? Could you just regenerate your static site when the database updates, thus allowing you to keep serving static HTML?
its various little annoyances: rebuilding a site can be tricky when you are on the move (say with a mobile device) and just want to add/edit a bit of content. or to give editing access to non-technical people. or the search capabilities that are more powerful with a db etc.
it feels that between the spartan austerity of an SSG and an overengineered full-blown database-backed CMS there might be some intermediate option. or maybe not :-)
Oh, those are interesting issues. I've had a similar hankering but for me it's 99% just because I want a nice comments system. I've toyed with the idea of taking a project like Issi and rolling up a SaaS based on it which basically provides an SQLite comments system. Paste one line of JavaScript into the page, and boom.