iPhone SQLite DB and Web-based DB synchronization and interaction recommendations
You'll need to write your own synchronization engine. I posted a lengthy set of notes on a record-level, history-driven synchronization engine I wrote from a wine journal application, which you can find here…
If you are looking for an existing API the QuickConnectFamily framework has one that works within the UIWebView using JavaScript for both in browser and installed SQLite databases. I'm also close to having a pure Objective-C implementation for those that aren't writing hybrid apps.
The javascript version also works for Android.